Eh... they do sting other corals. They are the tapetum sp not the tulips.
I HAD some till my peppermint shrimp decided they were tasty and ate them all in the span of a day (after living with them for nearly a year).
I got them from Gary M here on RC. I'd be interested in getting some more if anyone might like to do a group buy, I'll be willing to talk to him about it. (I'm not sure if he's still selling them though)
I gave a few away to a couple local reefers.. one since left the hobby and I have no idea who he sold his system to, the other had a wipe out crash that killed "everything" they had.. including these generally durable lil guys.