|Like they're easy to photograph. Especially when you're being cautious with the waves to keep your feet dry.|
Anyway, it was quite small (maybe 4 in. diam.) and it didn't have the internal structure of a moon jellyfish.
My best guess looking in the book later: Many-ribbed Hydromedusa. but...but...! On the web, I learn that here is where good old GFP
comes from! (so let's give it the scientific name here) Wow, if only I still knew anybody who could possibly find that remotely interesting...
Randomly passes through to offer the following trivia: you know how a jellyfish is a cnidarian, right? Right? Come on, play along. "Uh, yeah, sure." Apparently cnido- is something like sting. Went to my dictionary and, uncharacteristically, it didn't feel like giving a decent etymology to confirm this, but something like that.
Jellyfish might equal cnidarian precisely, but I don't know for sure.