After my tank up grade a couple months ago I lost a couple small sps colonies. Now i am not sure how or if to remove what is left of them. I have cut all the branches down the best a could, but now am left with two spots that are about a 1/4" thick or more and about 2-3" in diameter of dead acro skeletal structure. They are quite ugly and in prime real estate. These chunks are.. well hard as a rock.. The rock is not easily removed. I have chiseled away with some slow success. Should/Could I just leave them, placing a new acro on top hopping to have it grow over it? Is it a problem to leave it.. will it blend into rock sooner or later? What can I do with this?