Can sponges be motile?

[Akwarius]

Is it possible. I just added an (unanchored) softball sized red sponge to my dt about a week ago. Every morning I see that it has moved from the crevice that I lodged it into and every morning I put it back. Is it moving like an anemone or being moved by cuc, etc. ? And what is the safest way to attach it?

 

[Bongo Shrimp]

It is probably being moved by something- current, CUC member, or just falling down. Attach it either with a thin rubberband or by shoving a toothpick into it and shoving the other end into where you want the sponge to go.

 

[Akwarius]

Thanks. I'm going to try breaking it into two or three smaller pieces and attaching them to the lr with toothpicks.