The Nagasaki Prefectural Police said Tuesday they had captured a horseshoe crab at a supermarket parking lot in Sasebo.
"Someone probably caught (the crab), played with it and got rid of it once they were bored," police said of the endangered crustacean.
A supermarket customer spotted the 66-cm-long crab at around 6:30 p.m. Monday, according to police.
The crab perked up once it was put in a water tank at the local aquarium, Saikai Pearl Sea Center.
"Since the parking lot is more than 1 km from the seashore, there is no way (the crab) got there by itself," an aquarium worker said.
Horseshoe crabs are found in Shikoku, northern Kyushu and the Chugoku region.
They are an endangered species and the government has designated several of their breeding grounds as natural treasures.
