Hidden Spore Launchers Help

[fdrpi]

I've just discovered this game, and the following chain of events has occurred multiple times: an unseen spore launcher rips through all of my improvements. I send my units out to look for it, to no avail. Then, several turns later, it just "appears" a few squares from my base, on a square where I swear I should have been able to see it with one of my units if not the base itself. Repeat ad nauseum.

What is going on? Why are the launchers hidden, and what can I do do find them quickly?

 

[Noire Leblanc]

If I'm remembering right, the xenomorphs can hide in xenofungus.

 

[Buster's Uncle]

A sensor in that area would help - but yeah; frequently a spore launcher won't be visible until one of your units tries to enter its square.