Bizarre critter found

[Armando]

Wow, i just found this strange thing crawling on the front glass after lights went off. It is paper-thin so it is definitely not a stomatella snail. It's not a clear flatworm because of the shape, and also because it's huge. After I turned the room lights on it quickly ran into under the rocks

Does anyone know what is it?

 

[synchiropi]

Some type of sea slug?

 

[NateHanson]

Judging from the picture quality, I'd probably guess it's the Loch Ness monster.

How big is it? Did it have legs?

 

[Armando]

hehe... I posted on Dr. Schimek forum but (as usual) I got a disgruntled response LOL