Help with identification

[cheltz143]

Can someone tell me what this is? I was told it was sponge but not sure.

 

[Oceanwave45]

Picture??

 

[cheltz143]

 

[Oceanwave45]

It's a sponge for sure... what type it's hard to tell...

 

[cheltz143]

It has grown very fast since we first got it. Almost tripled in size.