TOKYO: Hundreds of horseshoe crabs — known as “living fossils” as they are among the earth’s oldest creatures — have washed ashore dead in southern Japan, confounding experts who study the alien-like sidewalkers. Horseshoe crabs, known for their blue blood, are a regular summer visitor to tidal flats in south and western Japan including one near Kitakyushu city where they lay their eggs. Some invariably die in the process, but this year a local conservation group noticed that the number of the precious marine arthropods that perished was unusually high, a local official told Agence-France Presse on Thursday. “The conservation group spotted about five to 10 remains every day during the egg-laying period, so they started to tally them,” said Kitakyushu city official Kenji Sato. “In total the number of dead horseshoe crabs reached about 500,” he added.