Need help identifying

[kiet_kat]

Moving my hammer around the tank and noticed this on the base. It is also on a different hammer also. Pest?

Thank you in advance

 

[WV Reefer]

Moving my hammer around the tank and noticed this on the base. It is also on a different hammer also. Pest?

Thank you in advance

looks like a sponge to me. Most of them are harmless but a few types can grow quite aggressively.

 

[vetteguy53081]

Syconoid sponge and harmless filter feeder

 

[kiet_kat]

Thank you! I was concerned something might crawl out of it