What in the world?

[Foxchase]

So over the past few days I've noticed these clear things popping up over my rocks. Never seen anything like it and can't find anything anywhere about them.

 

[samnaz]

Sponges... maybe?

 

[xxkenny90xx]

Are they hard or soft?

 

[PTXReef]

Sponge, I like to manually remove as much as I can (pretty easy to do as they fall off pretty easily). Harmless filter feeders but IMO don’t let them overgrow onto a coral, it may slow coral growth.

This is an acan frag that was covered in them. Pic is before removal with tweezers: