There are only so many ways to design a ball of energy, Rae. Any visual resemblance could easily be chalked up to coincidence, and you can't build a lawsuit on coincidence.
No I'm sure it has to at least have a little difference in apperence rather than just the name otherwise it can be saw as stealing a copyrighted idea. I mean you can't just take a picture, for example, from some one else rename it and call it your own you can however base a your own drawing on their idea just as long it is not an exact copy.