it looks like the base of a coral that was broken off and it has healed over. You will probably have to wait for it to grow out some more before you can get an ID.
thanks guys, it definitely does not look like a millipora and i dont think its the base of an acro, it is about 3 inches so its not a small frag. the base of it is blueish-greenish that fades to yellow-greenish with purple or blue pollyps. Either way it was a good find and im happy. Cant wait for it to grow more and show its true collors.