Ah, the monitor I was using earlier sucked. That appears to me to be a Condylactis gigantea, the Atlantic anemone. Can we see a picture of it outside of the bag?
I think it is a Condy as well.
I do not know why TBS would ship it when they knew my tank was new. (It wasn't a hitch hiker, it was bagged and everything)
Those things are basically weeds, they are easy to keep alive and require low light. Good starter anemones. However, they also have a very potent sting and do not host any fish. I've had wrasses devoured by them (way back when I started and knew nothing about them) that cost 6x the value of the anemone. Unless you want to keep an Atlantic species type tank, I'd suggest getting rid of it before you put in more fish or corals (like I said, the sting is mean). Just me opinion of course...