What if your turtle has algae like material hanging from his shell?

i don't no but here's how to get rid of it -They can have a warm salt water bath. It is a cure for fungus but it should work for the algae too. At least 15 minutes. Repeat daily until gone then weekly? For fungus, you would continue to treat after it looks like it is gone-like antibiotics, you want to make sure it is all healed.