Sponge or something else?

[Denizzz]

Hi, few things have appeared on my rocks. They look like clear silicone. not a moving thing. Sponge or anything else?

 

[MrWheelock]

They look like pineapple sponges to me. Harmelss filter feeders. +1 for diversity!

 

[vetteguy53081]

Sponge(s) - yes

 

[gillskills]

Definitely pineapple sponges. Help keep water clean and if you have space for a dwarf angel, they’ll love you for having these in your rock

 

[Auquanut]

The first picture looks like a sponge. Can't really tell in the second one.

 

[Denizzz]

Updated photo: I am almost sure of sponge. But not pineapple one.

 

[KJ]

All are sponge.