What is this?

[Daddio64]

I got this a few months ago, they said it was a mushroom. Hasn't changed much it was part of a 13 for a $100 frag deal so wasn't to picky when picking them out. Hasn't melted so it's still alive. I'll add a picture for perspective.

 

[Stealthreefer]

Looks like a completely bleached out mushroom to me.
Put it lower in the tank.