oh, cool mission. I've added it!
It looks like Anthopleura elegantissima
http://bit.ly/usqfEI -- this page has a great description
I also think it's a Pacific Sea Lemon. Peltodoris/Anisdoris
definitely a type of chiton. beautiful!
Wow, I love to see them swarm. Anyone sure on the species, the wiki link for the Red-veined Darter doesn't indicate they live in the Pacific Northwest of the US...
oh, yes--on the beach in Newport, Oregon.