Are these sponges?

[Fishy888]

I think I have two types of sponge here although I might be totally wrong.

There’s a larger single one and many smaller ones, much like stars in the night sky. Please let me know if these are sponges or something else. Thank you.

 

[blaxsun]

The big one in the center is definitely a sponge.

 

[Fishy888]

The big one in the center is definitely a sponge.

Thank you.