I don't have my old 90g show tank for many reasons. The main one being that it sprung a leak. Also, time goes on, and so do changes of living spaces and careers. If you check out my "some of my old tanks" thread, I've had many, many more tanks then that.
Yes, that is a serpent star... grew really big. Once I put him in the tank, I only saw his legs every now and then. He ended up being about 3 foot long from tentacle to tentacle by the time I lost track of him.
That's called a "Mushroom Anemone" It grew to about 10-12" wide before my tank sprung a leak. It died in the move. When I bought it, it was the size of a quarter, for $5. lol!