Unusual 'Sea Butterflies' (thecosomes) On Beach

Observation: This is a critter we have never seen before. They are washing ashore between Seldovia's inside beach and MacDonald's Spit. They are clear and have a very bumpy exterior that feels a bit leathery. One was found with what appears to be its insides still intact and moving. We don't know if it is a colonial type jelly (like a Salp) or an egg or some sort.

Update - Michael Opheim added on August 14, 2016. "They are Sea Butterflies and are in the mollusk family. You can find cool videos on YouTube. Here's a video link. See also video

Northwest Boreal LCC Network Consult: Regional Fish & Wildlife Biologist, Glenn K Chen writes, "Ah, these are Blobidus transpareti, a marine invertebrate found in Kachemak Bay. These gelatinous remains are interesting albeit difficult to identify ... The bumpy surface with small nodules is most curious, reminiscent of the dorsal surface of a (very large) dorid nudibranch, or perhaps a sea cucumber -- but neither of these are transparent. Perhaps these see-through critters may have had tentacles of some type (?) which would then suggest Cnidarians or something similar (?). Will keep puzzling about them..." GC - (2016-08-10)

Auke Bay Laboratories Consult: Ecosystem Monitoring & Assessment (EMA), Kristin Cieciel write, "The Genus for that specimen is Corolla, species I think is spectabilis its common name is the sea butterfly." NOAA Fisheries (2016-08-26)

LEO says: For more information see video: Monterey Bay Aquarium Research Institute (MBARI), 'There's no such thing as a jellyfish'. Another good source is: What's in your ocean? jellywatch.org: "By all accounts, jellyfish are creatures that kill people, eat microbes, grow to tens of meters, filter phytoplankton, take over ecosystems, and live forever. Because of the immense diversity of gelatinous plankton, jelly-like creatures can individually have each of these properties. However this way of looking at them both overstates and underestimates their true diversity. Taxonomically, they are far more varied than a handful of exemplars that are used to represent jellyfish or especially the so-called "true" jellyfish. Ecologically, they are even more adaptable than one would expect by looking only at the conspicuous bloom forming families and species that draw most of the attention. In reality, the most abundant and diverse gelatinous groups in the ocean are not the ones that anyone ever sees."