This isn't really a SPOILER...
Here is a photo of the mural painted on the wall of the ampule temple chamber room with the giant head.
Upon closer inspection, they seem to have incorporated H.R. Giger's artwork into the mural itself. His original concept illustration of a bulkier Facehugger can be found in the lower-right corner...
...and an earlier design with thinner tendril appendages wrapped around the victims neck, mirrored on the opposite left side of the mural.
The entire mural seems to be a psuedo re-imagining of this Giger piece depicting the Alien life cycle for the original 1979 film.
Could this mural wall painting be an early rendition of the Alien life cycle? The proverbial xenomorph 'Tree of Life', as it were? Why did it start changing?
Could it also be a large door?