As small as it may be, the dinoflagellate Dinophysis makes itself known to humans in an unpleasant way. Mussels consume a toxic substance excreted by dinophysis when it blooms and people eat mussels. When concentrations are too high, the mussels are dangerous to eat. The mussel itself suffers little from the harmful algae, however mussel-eating people can suffer from intestinal and stomach disturbances. Fortunately, after a couple of days of nausea, the only remaining effect is that it will be a long time before mussels are eaten again.