Not really a critter but some kind of seaweed

this was taken in Jupiter Florida on the wreck of the Miss Jenny (I'm pretty sure, or it could have been the Zion) Does anyone know if it has a common name? Thanks.

Hi Ellen -- It's a Caulerpa. The ones that look like this are often called green feather algae.

Thanks Leslie. That is the perfect name for them. I was mesmerized by them. They were so pretty.