In springtime, when the rain gathers into pools in the Dasht-e Lut, a desert in Iran, the sand comes alive.

Tiny, desiccated eggs, buried among the ginger-colored granules, drink in the water and begin to hatch. Some may have been laid in the dunes decades ago. But when rains come, the eggs unfurl into small, feathery crustaceans called fairy shrimp, the freshwater cousins of brine shrimp. For a month or two, the fairy shrimp frolic, swimming upside-down in their ephemeral lakes and laying their eggs before they die or the pool dries up, whichever comes first.

Fairy shrimp live in brief spurts in seasonal ponds throughout the world, from steppes in Mongolia to woodlands on Long Island, New York. But the Lut Desert, often called the hottest spot in the world, may be the last place one would think to find water, even seasonally. In 2005, NASA’s Aqua satellite recorded a ground temperature of 159.3 degrees Fahrenheit.

The researchers described the new species, Phallocryptus fahimii, in the journal Zoology in the Middle East.

Hossein Rajaei, an entomologist at the Stuttgart State Museum of Natural History in Germany and an author on the study, was the first to spy the shrimp. He had come to the Lut in March 2017, his second visit, on an expedition of 17 people to observe the insects that lived there.

In Farsi, Dasht-e Lut translates to “desert of emptiness.” “I suppose they gave it this name because many people believed there was no life in this desert,” Rajaei said. Recent expeditions have uncovered an unexpected diversity of spiders, lizards and other fauna, but the life that has been described in seasonal ponds was limited to single-celled archaea.

One day, a little before noon, with the sun high and blazing, the expedition found a lake glimmering in the middle of the desert like an oasis. Rajaei had never seen a lake so big in the Lut, but the desert had experienced its first heavy rainfall after a decade of drought. The 87-degree water — the temperature of a warm, creamy soup — felt refreshing in the immense heat, and as Rajaei waded in the shallow pool, he saw milky white creatures swimming around, leaving trails of tiny bubbles. Hadi Fahimi, a herpetologist, and Alexander V. Rudov, another author on the paper, joined Rajaei in the water, and together they scooped up the animals with an insect net.

“We were all very happy to find this tiny shrimp here,” Rajaei said. Some female specimens he collected had iridescent, emerald-color eggs shining through their bellies as they swam upside-down.

Unsure whether the shrimp was a new species, Rajaei asked Martin Schwentner, the paper’s lead author and a researcher at the Natural History Museum of Vienna, to take a look. When Schwentner compared the genetics and morphology of the shrimp with the four known species in the genus Phallocryptus, he determined that the shrimp was a new, fifth species. The morphological differences between the new shrimp and a Mongolian fairy shrimp, Phallocryptus tserensodnomi, were slight: a longer frontal organ, and curvier antennae.

According to Alonso, the researchers did not make an unequivocal distinction between the morphology of the new species and that of P. tserensodnomi, which is found in Mongolia, and P. spinosa, which is found elsewhere in Iran. “The morphology is tricky,” Schwentner said, “but the genetic difference made it obvious that it was a different species.”