I would leave it in the sump and watch it. Just make sure I can't get caught in a pump. Cause if it is a cucumber and It perishes it could wipe out your whole system.
I had a tiger barb cucumber get caught in a mp40 a few months ago. I thought it was toast. But I didn't care and tossed it back in the tank. It hid under a rock for a few months not moving. I forgot all about it then like a month ago I saw it out and walked around the other side of the tank to see I had another one. The dam thing split on me.