its almost impossible to to pick off and it feels almost like velcro.. they aren't very tall so its hard to see if it has the fern like shape.. Its a Biocube 29 so i think the tang police would have PETA at the door quick.
Maybe post a picture of the rock in the tank. If it is bryopsis you can use tech m made my kent to raise young levels and that will kill it. I just did this in my 220 reef tank. Killed all of it in about 5 days. I raised mine to 1600-1700 and the bryopsis turned clear and my blenny ate it.