OMG a monster in my tank!

[corpusse]

Looks to be a polyclad. Not sure exactly what kind but be warned, some will eat snails, calms and other things you don't want eaten.

I had a quite a few in my tank years ago losing many snails, a baby clam, and even my sanddollar. I would remove it to be safe.

Just a couple weeks ago when I moved some rocks I found another. So if you have one, you likely have many.