I don't think this nem is a bta. There seems to be some verrucae on the underside, and if I remember right, bta's don't have these bumps.
As for what it could be, I don't think I could come up with something. Some members in the Heteractis and Macrodylactis (I don't know if I spelled that correctly) have verrucae, but colors and patterns vary.
Do know what kind of nem it is? If not, you may want to post a nem ID, that might help on caring for it at this point and give you an idea of how it may heal.
Good luck!