Alien: Covenant
How does a Xenomorph mature into its adult form?

How does a Xenomorph mature into its adult form?

16,820 Views17 RepliesAdd A Reply


TrilobiteMember9516 XPNov-15-2016 5:48 AM

One scene we have never seen in any of the Alien movies is exactly how a Xenomorph is capable of growing from a Chestburster, averaging eighteen inches in length, into a fully grown nine feet tall adult, seemingly within a short period of time. Thankfully though the installments in the franchise so far have given us some clues.

The first thing we know is that during or before its transformation the Xenomorph Chestburster sheds its soft tissue. Even the variant that was born on Fiorina 161, which was born more developed than that of a human-born Chestburster, was shown to have shed its soft tissue before maturing into its adult form. Ironically this piece of "common knowledge" was completely overlooked by most fans (as well as concept artists for Prometheus) when Scified ran its popular design the adult deacon competition, with most interpretations of the deacon shown with adult sized proportions. Some entrants did, however, incorporate the exoskeletal trait previously seen in adult Xenomorphs, suggesting that the Deacon too would have shed its "burster skin" before maturing.

Next, we know that the Xenomorph grows from its Chestbuster form into an adult in a very short time frame, possibly even mere minutes. One would imagine that such a biological process would be violent and painful if kept in line with the design aspect of the creature (more on that later). During this process, one would imagine that the Xenomorphs body would be pliable and soft as it expands and grows exponentially in size. Upon reaching maturation the Xenomorphs skin would then slowly solidify, as evidenced by the possible molting evidenced by various specimens, in which it would appear that the Xenomorph sheds multiple layers of its adult skin before fully maturing. It is also possible that what we have witnessed as molting is instead evidence to an alternate form of maturation we have never even speculated upon (but again, we'll cover that later).

Another element of the Xenomorphs maturation that has been inferred is that the Xenomorph is capable of maturing a second time. The inference is that the Xenomorphs that overwhelmed the Hadley's Hope colony had once had the smooth, translucent carapaces like that of the specimen that terrorized the crew of the Nostromo, but in the interim period before the USS Sulaco arrived the "Drones" shed their crowns and became "Warriors". The critically panned crossover AVPR postulated something similar, claiming that its Pred-Alien was a juvenile Queen or Princess that would somehow later have developed into the more familiar Queen. The Dark Horse comics and many video games have added to this concept even future suggesting that a Warrior caste Xenomorph is capable of maturing yet again into a Praetorian, which can then mature once more into a Queen, giving the Xenomorph multiple possible stages in its lifecycle dependent upon the composition of its brood, or lack thereof.

Returning back to the Chestburster, the most inferred scenario seems to be that upon shedding its soft tissue a Chestburster finds a secluded spot before violently undergoing growth into its adult form. Another possibility, though less likely as it would move away from the nightmarish visage of the creature, would be that to transform from a Chestburster into its adult form a Xenomorph could cocoon itself within a chrysalis a secreted resin, within which it could quickly gestate into its adult form. It is possible that what we have witnessed as molting could the residue from within the cocoon, but having never seen any other evidence of the cocoon this scenario is unlikely. Yet with Sil the antagonist of Species having also been designed by the late H. R. Giger, it is possible that its inspiration could be retconned into the Alien franchise.



Do you have any theories or facts on this unseen aspect of the Xenomorphs lifecycle?

17 Responses to How does a Xenomorph mature into its adult form?

Darth Shiro

ChestbursterMember883 XPNov-15-2016 6:36 AM

Nice theory!

Dinosaurs incredible creatures who roamed the Earth 65 million years ago. Never had nature been filled with so much terror and beauty...

Something Real

TrilobiteMember5639 XPNov-15-2016 8:50 AM

GAVIN SINGLETON - What an incredibly intricate hypothesis! I happen to believe there is a significant amount of weight behind this presentation! Thank you ever so much for taking the time to create this and share it with us! :)


FacehuggerMember349 XPNov-15-2016 9:41 AM

i use to think that the chest burster developed a hard outer shell around it making the dome head where it would crawl around like a beetle before developing the rest of the body the chest burster becomes the inner jaws and the primary jaw develops a stupid theory i use to have when i was ten XD

"i dont know what weapons will be used in world war 3 but i know what wil be in world war 4...sticks and stones"Albert Eienstien


XenomorphMember1234 XPNov-15-2016 2:21 PM

The Aliens RPG says chestbursters eat (anything really- organic or inorganic) to reach full size.  Which recalls the deleted food locker scene from Alien.  After reaching full size they only eat to heal or generate webbing.

Veronica Cartwright has mentioned that it went from white to black as it matured because it was bruising from growing so quickly.

The simplest idea is that they have an incredibly enhanced metabolism that kicks in when they're still an embryo, and stops when they reach 7-8 feet in height.

The gestation and growth times vary wildly.  Kane was in the ballpark of 16 hours for gestation and less than two hours to reach full size.  The Fiorina creature however, emerged more developed, but was still only adolescent size when it killed Murphy over 10 hours later.  It's gestation was closer to Kane's however (around 15 hours).

Dialogue about rapid growth of the Auriga creatures was deleted (probably not even shot).  AvP went to a ridiculous extreme of gestation and growth in under 10 minutes (but that could be explained away by the Predators mucking about with the Queen).  The Gunnison creatures spawned by the crash had a more normal gestation - around 8 hours.


PraetorianMember2267 XPNov-15-2016 6:31 PM

very cool post about the cycle theory! I hope we get to see something resembling the xenomorph's growth cycle with these mutations in Alien Covenant




 "Must be something we haven't seen yet.."__Bishop


Sci-Fi King25

PraetorianMember4297 XPNov-16-2016 12:39 PM

Adding on to the cocoon theory, maybe those tubes on a Xenomorph's back are what releases the resin?

“Banana oil.”- George Takei, Gigantis: The Fire Monster


XenomorphMember1234 XPNov-16-2016 1:51 PM

I doubt they coccoon themselves to grow.  It would make them vulnerable.  Plus we see the 'mid-stage' in Alien3 when the Alien kills Murphy.  But that creature didn't have the dorsal tubes.


EngineerAdmin23332 XPNov-16-2016 4:54 PM

Very interesting topic indeed. The rapid growth definitely would be a painful endeavor and usually, growth like that results in a shortened life span and malfunctioning limbs and joints. Yet, the Alien seems fine when it's fully mature.

I really like the mention of the Alien being white but turning black due to extreme bruising - nasty!

My theory is more inline with what S.M mentioned - in order to produce energy and fuel a metabolism, you need fuel. For us, it's calories. The Alien clearly requires the same nutrients we ingest or the Facehugger to Chestburster process would be a waste and Aliens could simply just "grow on trees" (Covenant reference...).

With that understood, it's safe to assume that the Alien does require food, or some form of caloric intake to fuel it's insanely fast metabolism. I also feel like they shed multiple layers and multiple exoskeletons as they grow. 

It's interesting to note however, in the AvP RTS game Aliens vs. Predator Extinction, the Aliens DID cocoon prior to emerging fully grown. So.. it is still a possibility and we could simply have not seen it yet.

Alien: Romulus - New Alien Movie Coming Soon! Visit for more info!


XenomorphMember1234 XPNov-16-2016 5:07 PM

Something that challenges the need for food to reach full size is that there's no evidence the Aliens ate on the Auriga.  There's no obvious remnants or remains of food in the cages.

In fact apart from AvP:R, and some questionable scenes in Alien 3, there's no evidence they eat at all.


EngineerAdmin23332 XPNov-16-2016 5:35 PM

But where would they get the energy from?! If they used sunlight and converted it to energy the way plants do, okay, but Aliens come out at night and rarely are ever seen moving about in the light. 

If they don't eat then they must have some truly "Alien" method for producing energy to grow and move around. 

Alien: Romulus - New Alien Movie Coming Soon! Visit for more info!


XenomorphMember1234 XPNov-16-2016 6:00 PM

"But where would they get the energy from?! "

That's the million dollar question.

The old RPG also mentions they can access solar energy, static electricity and direct current.  The energy generated by a light breeze is sufficient to sustain an adult.

It could simply be that they're efficient enough to grow to full size on whatever was gained from the host.


EngineerAdmin23332 XPNov-16-2016 7:29 PM

Electric current I could buy, even solar energy despite them being primarily nocturnal. But air? That would require some explanation haha.

But what would cause the Aliens to lay dormant? It seemed as though until the Queen signalled them to attack or hosts walked near them that they remained relatively lifeless. 

Alien: Romulus - New Alien Movie Coming Soon! Visit for more info!


XenomorphMember1234 XPNov-16-2016 8:27 PM

I think they were getting at kinetic energy from a breeze is enough to keep them 'charged'.

As for why they were dormant - conservation I would assume.  They guess there's no more hosts, so they'll just sit and wait until more show up.


ChestbursterMember729 XPNov-20-2016 4:59 AM

I remember an old theory that Xenomorph Chestbursters eat any material they can get their two jaws on to use to fuel their growth, be it a cat (ala the AVP2 video game), or simple metal and other miscellaneous material.

It would certainly explain how they manage to get the physical material required for growth, and would add an element of mystery as to why a creature would have such a resource-efficient growth process in the first place.


TrilobiteMember9516 XPNov-20-2016 2:54 PM

Time for me to chip back in on this one, me thinks.


As S.M. mentions there is next to no evidence in the movies that shows that the Xenomorph eats before transforming from a Chestburster into an Adult. One suggestion could be some form of hyper-accelerated metabolism, but remember that the Xenomorphs that took over Hadley's Hope could not be seen by the Marines infra-red visor - I know some will argue that the creature probably produced heat equivalent to that of the ambient temperature of the hive, which Huson called a "Dry Heat", but if the Xenomorph does emit such heat wouldn't such heat have alerted Ripley to the Aliens presence when it hid aboard the Narcissus escape shuttle.

While there is no evidence to support my theory, I like to think that the answers stem from a reservoir of the notorious Black Goo from Prometheus, stored somewhere within the Xenomorphs biology. When transforming into and adult a Chestburster sheds its silicon skin, revealing its exoskeletal frame and "sweats" the black goo, causing the maturation process. When fully grown the Adult Xenomorph then uses the gases and heat emitted from the Black Goo's viral cells reproducing within its "bowels" to fuel its heightened mobility as well as its accelerated healing. It may also be possible that the Xenomorph uses this internal reservoir to transform a host into an egg, and that the Queen may use the reservoir to fuel her endless productions of eggs. But thats just my theory.

Though, the more I think on it, my theory could explain the importance of the Black Goo in Prometheus and its "DNA" to Alien/Aliens? Hmmm...


DeaconMember10416 XPNov-20-2016 3:14 PM

Interesting Topic i missed.... when i am less busy i hope to add my two cents... but its something pretty much been mentioned already on here.

R.I.P Sox  01/01/2006 - 11/10/2017


NeomorphMember1984 XPJul-19-2017 5:35 PM


Add A Reply
Log in to Post
Enter Your E-Mail
Enter Your Password

Stay Logged In
Alien & Predator Alien & Predator Fandom
Recently Active Forums
Alien Games
Alien Games Discuss Alien games here
Alien Discuss all things Alien here
Alien FX TV Series
Alien FX TV Series Discuss the Alien FX TV series here!
Upcoming Alien Projects
Upcoming Alien Projects Discuss new and upcoming Alien movies and TV series here
Hot Forum Topics
New Forum Topics
Highest Forum Ranks Unlocked
89% To Next Rank
80% To Next Rank
52% To Next Rank
NCC 1701
NCC 1701
27% To Next Rank
24% To Next Rank
Latest Alien Fandom Activity

Alien: Covenant is a sequel to 2012's Prometheus as well as a prequel to 1979's ALIEN. Alien fans looking to know more about Alien: Covenant should check back often. is an information resource for film enthusiasts looking to learn more about the upcoming blockbuster Alien: Covenant. Providing the latest official and accurate information on Alien: Covenant, this website contains links to every set video, viral video, commercial, trailer, poster, movie still and screenshot available. This site is an extension of the Alien & Predator Fandom on Scified - a central hub for fans of Alien and Prometheus looking to stay up-to-date on the latest news. Images used are property of their respective owners. Alien: Covenant, Prometheus and its associated names, logos and images are property of 20th Century Fox and are in no way owned by Scified and its related entities. This is a fan-created website for the purpose of informing and exciting fans for Alien: Covenant's release. If you have any questions about this site, its content or the Scified Network in general, feel free to contact Scified directly.

© 2024
Sign in
Use your Scified Account to sign in

Log in to view your personalized notifications across Scified!

Jurassic World
Aliens vs. Predator
Latest Activity
Search Scified
Trending Articles
Blogs & Editorials