Anemone swallowing all tentacles?
 

Looked in the tank & all were well. Hour later all that was visable of our Condi was a round white disk with a small hole in it...looked kinda like a sponge. Almosted panicked, but didn't look mushy at all...just no tentacles. Awhile later 1/2 hr or so & tentacles are reapearing & reinflating. Anyone seen this before? Is there a cause, or just a thing that they do?

In my experience with LTAs and Carpets, they just do it when they get "freaked out" by something, my guess is a defensive mechanism.

If you have clowns, they will protect it like mad when it curls up, so watch out, mine scared the crap out of me when he nipped at me the first time!

i've also seen them do that after feeding. you will likely see it often. I wouldn't start to worry unless it looked like a blob of mush a few hours.