Friend rehomed a tank to me a week ago. It's got this thing in it, now named 'Madam Doohickey'. Friend says "she thinks" it's a mushroom coral. If it is, I don't know what kind and can't seem to match any pictures to it. Green tentacles retract into the off-white base. Maybe 1-1/2" tall on a stalk. I love it, but what the heck is it?