No, algae at all. These rocks are fully cured. I have seen worms, and a few other things that I can't desribe. Even things like feather dusters. I also think there are little anemones attached to the rocks. I say anemones cause they have alot of tenticles stretching out during the night and sometimes during the day. The rocks are under T5's for about four hours and three hours of actinic. What do the anemones and the feather dusters need to survive?