[Delphinus]

It sounds like it could be. What I notice in the spread of mine is that sort of matting extending out into new territory and then GSP sprouting out of that mat. But the one thing that I've noticed in mine anyways, is that it tends to be in one big contiguous clump -- i.e., the colony just gets bigger. Unlike, say for example, xenia, I haven't so much noticed pieces breaking off and starting new colonies in different places (although I suppose that could be possible -- it just hasn't happened in my tank..). HTH..