California clam shrimp (Cyzicus californicus) at a vernal pool in Sonoma County, California. Clam shrimp are branchiopod crustaceans related to water fleas, brine and fairy shrimp (sea monkeys), and tadpole shrimp. Like their relatives, clam shrimp spend most of the year as drought-resistant eggs buried in the sediment of dried pools, hatching after the pools are filled by seasonal rains. Once hatched, they have anywhere from a few weeks to a couple of months to grow to full size and produce the next generation of eggs. If you look closely at the water of the pool you can see a couple of barely-visible clam shrimp swimming close to the surface. The turbid water is the result of the clam shrimp stirring up the sediment as they filter out food particles.