Applied to the Scott Movies

Ati

Mutagenic pathogen (black goo) --> Host --> Hybridized creatures are produced (trilobites, insect-like motes, parasites) --> Host again --> Xenomorph-like hybridized creatures are produced (deacon, neomorph)

Applied to the movies:

Prometheus:

Mutagenic pathogen (black goo/virus) --> host (Holloway/Shaw) --> hybridized creature (trilobite) --> host again (the last Engineer) --> xenomorph-like hybridized creature (the Deacon)

Alien Covenant:

Mutagenic pathogen (black goo/virus) --> host (fungus) --> hybridized creature (insect-like motes) --> host again (Ledward) --> xenomorph-like hybridized creature (the Neomorph)

Mutagenic pathogen (black goo/virus) --> host (Planet 4 Engineers) --> hybridized creature (parasites bursting from the dying Engineers) --> host again (not revealed in the movie) --> xenomorph-like hybridized creature (not revealed in the movie)

Alien (1979):

/Mutagenic pathogen --> host(s): segment of the process controlled by the Engineers or David 8/ --> hybridized creature (facehugger in the alien egg) --> host again (Kane) --> xenomorph-like hybridized creature (the 1979 Xenomorph)

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Parasite clusters bursting from the Engineers:

The strangest thing, my favourite one, it looks like Satan's head bursting from the body, ring in the nose:

Snake-like clusters:

The spider cluster:

The monster cluster:

A very long one:

The funnel:

A traditional after-party cluster: -- :D --

Source: http://avp.wikia.com/wiki/Chemical_A0-3959X.91_%E2%80%93_15

And an exception, not parasites, but black goo - evil black goo clusters racing in the air:

Davefried81

I found the black goo popping out of them very interesting.  This goes back to the fact that there are many "different" strains of the goo-

Ati

I accept the explanations shared by the source article, so I think that clusters of parasites are leaving the Engineer bodies in the movie stills - not black goo. Ok, they look similar but they are different.

sherris

i still support the one goo theory.

Where one goo / pathogen exists and has various outcomes depending on host type (an Engineer and human may reract differently under the same comditions) -  amount of goo - ingested area 

However,only the one pathogen with the strength to wipe out all non botanical life on a planet if sufficient amount of the patgogen is dropped into the mix

Ati

sherris - Yes, the quantity is an important factor here. According to the source, Holloway and Fifield suffer the same mutation, but Holloway consumes only one drop, so he mutates very slowly.

Ingeniero

Ati, this analysis of the spider cluster release and the monster cluster bursting out is wonderful. I can't wait for the prequel novelization to come out this month.

Ati

Ingeniero - Thanks, these are just shapes, of course.

A L I E N 4 2 6

Just a little correction, I think its all spot on, but I think in Holloways case specifically, the black goo infected his........em......juices......which then took a detour into shaws uterus and got some mutating from the uterus. David used a similar process using shaws reproduction system, but instead of a trilobite and shaws uterus, he made it more efficient, making eggs and facehuggers.

Ati

A L I E N 4 2 6 - Yes, the Holloway process seems to be a special one, he is mutating at the same time...

Anything is possible, however, I think it shouldn't be over-explained and classified as an exception.