the way i see this monster , is like a mother that drop eggs in the water , the eggs become tentacles and later a pit worm that will be a new geneworm .

in my mod opposing life2life , the geneworm is right after the lab where freeman grabs the gauss gun .
the hydroelectric dam is having some models that looks like eggs with the sharks . in opposing force there is a tube system that appears with a garg death .
may be the swamp could have some tentacles and some scripts showing pitworm birth . pitworms being able to walk like ants , they could appear again in the last maps of game where one will become the final geneworm

in the same zone as the garg , that should be cool to open the way to the labs .
in that place , the player should find an update to the displacer that would make it very powerful : able to explode the garg by using all munitions at once .
that should be great for some nice video "effect"