My friend Sheila was the first to help us with the funny purple creature Hallie & I found on the beach.
Here is her answer:
"That purple little sea critter on your blog is a Sea Pansy (Renilla reniformis), a coelenterate & is a type of soft coral like Sea Whips & Sea Fans. Amazing to think about its being a colony of individuals. The "reniformis" ties back to it's being kidney-shaped ("reniform"). It is strongly bioluminescent when disturbed. The "stalk" anchors it in the soft sand & the "top" can deflate to lie closer to the floor in order to reduce resistance to currents or during rough weather. There are many tiny daughter polyps on the top which have 8 feathery tentacles each (see under lens). At least 2 small animals live on/with it: Beaded Sea Star (seeks protection there: commensal) & Sea-pansy Nudibranch (feeds on the polyps: predator or parasite)."
Wow. Just think about it. It is a whole world in your hand.
Thanks Sheila for sharing.