Semitransparent gelatinous structure

[meloles]

I have been watching this guy for about a month now. It is about an inch and a half wide. It hasn't grown much while I've been watching it. The tank is about 5 months old.

Type of sponge, maybe? It seems completely harmless.

Nevermind the hairy red algae. That's a whole different thread altogether.

Thanks for your input!

 

[bday1335]

Some kind of sponge