Sponge?

[davidm777]

I thought this was a sponge at first but tonight I noticed it has antenas. I have had this Elegance for a couple of weeks. Every now and then it shrinks all the way. Is when I've seen this thing... friend or foe?

 

[Euphyllia97]

Wow that reqlly looks like a sponge. Maybe the antennas come from a barnacle?

 

[davidm777]

Here with a flashligh

 

[Gumbies R Us]

@ISpeakForTheSeas

 

[Tahoe61]

Great looking sponge with exaggerated spicules.

 

[ISpeakForTheSeas]

@ISpeakForTheSeas

Sponge and most likely a friend (few sponges are problematic):

That's a sponge; the long spines sticking out are how these kinds reproduce asexually - they form buds that either drop off and grow into new sponges or just grow in place without dropping off. For example:
https://www.reeflex.net/tiere/14432_Tethya_burtoni.htm