I've seen tube anemones retract pretty quickly when someone gave the tube a tap (dive guides do this, unfortunately, because it leaves commensal shrimp exposed for photos). But I had no idea they actually moved around. I guess in this case the tube is just flush with the surface so we don't see it?
As far as I understand it, they can abandon tubes and pop up elsewhere. They make the tube so it's not impossible for them to do this. Some true anemones that burrow (versus ceriantherians) have u-shaped burrows and will pop up in different places. Wild!
Yup. I have real trouble getting my head around what they can get up to!