feeding tentacles

I was doing some poking around to consider fragging some mushrooms and suddenly the mushroom retracted and shrunk, and seemed to spew these semi clear worm tentacles like things. Are these worms in the shrooms or the shrooms tentacles? Thank you all for your support and advice!

So when I got these guys they were extending their tentacles every night for about a week. Ive had them for little more than three weeks and I saw one the other night extend maybe a tentacle halfway. Why is that?