Triops longicaudatus from Rodeo, New Mexico. These living fossils spend most of the year as dried-up eggs in the desert, and hatch when monsoon rains form large puddles. They grow quickly, eating fairy shrimp (also pictured in video), mosquito larvae, snails, and a variety of aquatic invertebrates. They attain a maximum size of about 4 centimeters before laying eggs as the puddles dry up. These animals have changed little in 70 million years. They swim with their many legs (up to 132 in …