Yep. Soak it in really hot water and scrub with a toothbrush (that is dedicated to aquarium use only, obviously). Don't use boiling water on painted or laquered gravel (the paint will flake off all over your tank) and don't directly boil your plastic plants (for obvious reasons...), but you can pour boiling-hot water over them. Let them sit in the water until they cool to handling temperature, scrub the yuckies off, then plop them back into the tank. Can't get simpler....except maybe by putting a fish in there that will eat the algae....