Do not kill them!! I believe they are rock anemones. Wait till others join in. We get rock anemones in all of the time at work. ( I work at a LFS in the SW dept.) They look identical, they come in different colors and are pretty hardy. I have never seen aptasia crawl, but anemones will "walk or crawl" to where they need to be. lol They do not host clown fish but can sting like other anemones.

Pretty nice "freebies".