New York's water is delicious—and filled with tiny crustaceans called "copepods". (Making it possibly not kosher.) H&E stain the water and put it under a microscope and you'll find these little guys. Crunchy closeup after the jump.
(And completely harmless. Copepods are even known to eat mosquito larvae, so don't think of them as invisible shrimp that are caught in your teeth—think of them as invisible shrimp who make NYC tap water taste fantastic. Like fantastic, quenching shrimp juice.)