Be a little patient with replies.
Anyways, I assume those are the little flesh mounts with tentacles around them? Those also came in the Battle For Macragg set and were objective markers used in that set. For the specific mission in Battle for Macragg, they spawned Spore Mines.
They have no actual rules in the game and are just extra terrain bits you get. I personally use them to base my nid-hunting space marines, to give them the feel of being on a nid-infested world. You can also just paint them up without gluing them to anything and use them as Objective Markers.