Are These Limpets?

[Fishfishfishfish]

I have these growing all over my sump. There is usually no light down there.

 

[Crabs McJones]

Looks like sponges and spirorbid worms to me. Very common sump dwellers

 

[Fishfishfishfish]

Looks like sponges and spirorbid worms to me. Very common sump dwellers

Thanks!