Golden Mauls's base turning green

[greengalaxy]

Hey I have a 22 gallon nano tank that has been established for 1-2 years. I have 2 clownfish, 1 chromis, 1 yellow watchman goby, corals, peppermint shrimp, and snails/ hermit crabs. Recently I have seen that the base of my golden mauls has green on them as if they had algae on them, and they don't open up that much. Is there any suggestion of what the problem is?

[jakejordan94]

flow issue maybe?