Now what is it?

[WayneSg]

Can someone tell me what this is? Seems like every time I turn around there is some new pest in my tank that I have no idea what it is or how it got there.

 

[ReeferBean]

Hard to tell but my guess is a vermatid snail.

 

[WayneSg]

Recently had my war with the vermatid snails. The little white tube on them was hard. These are soft and pliable. Also the one in the first picture was actually on the snail next to it and had moved by the time I got my phone.

 

[James M]

Looks like a sponge, harmless filter feeder

 

[WayneSg]

Like an actual sponge? Will it get big? Multiply quickly? Is that a nic name for something or actually a sponge? Thanks for any advice.