Id this critter?

[Caseyoidae]

I have found a few of these and can't figure out what they are. Nudis? They have a feather like "tail" sort of like a feather duster but they're white. They disappear then reappear by the bases of soft corals and under rocks. Very small maybe 1/4". Thanks and sorry for the bad picture.

 

[Caseyoidae]

Another photo.

 

[Tahoe61]

I need a better image, sorry.

 

[143MPCo]

Pineapple Sponge, filter feeder.

 

[Tahoe61]

Oh those are harmless pineapple sponges.

 

[143MPCo]

Another photo.

Yup, pineapple sponge!

 

[Caseyoidae]

Thank you! I finally got a better picture lol