Question: are rhabdocoela harmful to shrimp?
Answer: They are harmless to shrimp though I have seen them occasionally wiggle in and out of a ramshorn shell. Fauna is just part of a shrimp tank because typically fish eat the little dudes. But really, there are few critters that are truly harmful. Planaria, hydra, leeches, damselfly/dragonfly nymphs, and a few more.