Images: 

I snapped this photo while wading in the shallows during low tide at Matanzas Inlet on NE Florida's Atlantic coast on Nov 21, 2010.  I don't much about invertebrates; wonder if this is some kind of anemone?

I also took a photo in the same location of a Rough Sea Squirt (Stylea plicata - I think, based on an Internet search).  The creature pictured with this post has short, extended tentacles, and I don't know whether only anenomes have tentacles or if some other type of tunicate has tentacles, too.

Interested in hearing everyone's thoughts.