I am starting to see these in my tank. I'm not sure I've had them before and hoped someone could please help me identify them and if they are good or bad? Only in sump and drain areas. Not in main display...yet
They're definitely either sponges or tunicates - I'm leaning toward sponges due to the root-like base there, but I'm not confident on that. Regardless, they should be harmless filter-feeders, and they're pretty neat looking - especially that last one, which is quite unique.