The polyps extend fully every night when the lights are off and pulse during the day.
As for the nudibranch, you're correct. I've been researching him a bit. I'm pretty sure he's a quadricolor and not the Magnifica that I thought he was. Either way, they need a red sea sponge that I'm not putting anywhere near my tank. It secretes a toxin that's so nasty they're researching it because of it's effects on cellular life. I'm going to have some words with the store where I got him. Hopefully they'll take a trade, but there's no way they'll be able to keep him alive either. That sponge would kill everything in every tank connected to it, it'd be carnage in a fish store. The only bright side is I might get some extra clean up crew snails, and it's gotten me into researching sponges. I've got all the fish I want in this tank already, so now it's just mix and match time with corals until I figure out a good variety that works and looks good.