It's looking great whatever it is, but it sure looks like a smaller version of my crispa which now measures 18 inches across. The column in your earlier pics is what makes me think crispa most (looks like leathery verracue) and the lack of pronounced rings on the tentacles. But I've certainly been wrong about IDs before and could be with this one. Is it buried in the sand or attached to a rock at this point? If it's attached to live rock, then that would even convince me more that it's crispa. H. malu will bury in the sand, crispa occasionally bury in the sand but more likely attach to live rock.