Unknown things

[DHS]

Not really sure what these things are. They look sorta like cocoons with feelers on the ends. They do move around the tank though VERY slowly, and they seem to like algea. The two you see moved to the new calerpa, while other are located on a piece of bleached coral, & in my power filter. They don't seem to be harming anything I was just hopeing someone might be able to tell me what these things are going to 'grow' into.

Peace,
DHS

PS - Last thing added to the tank was the calerpa...but these things appeared before then.

 

[Anemoneman]

Sponges. Careful of the bristles, they can irritate your skin.
Harmless.