[Aliens]"...solitary giant predator caterpillars. Civilization wasn't easy for us"

[Kissamies]

'Kill the interloper! Rip out its life!' They are fiercely territorial and xenophobic, all right. I agree most of what you have done. Remember that in the game they have captain names like Master 36 or Death 111, which could imply a strict hierarchy, which would fit their territorial nature.

It's hard to ascertain the actual shape and size of the creature because there is no canonical full picture of it. The best I can tell from pictures it should probably be 1:5 ratio at least and ratio at least. A in a manual picture the face is larger than a Spathi, but we don't know how large a Spathi is, probably small. Personally I'd go for +2 or +3 from what is implied, but it's very subjective.