Japanese police have arrested three Chinese nationals in Amami Islands on Wednesday after discovering thousands of protected hermit crabs packed in suitcases.

According to Japanese police, the suspects Liao Zhibin, 24, Song Zhenhao, 26, and Guo Jiawei, 27, were found with about 160 kilograms (353 pounds) of live hermit crabs. Officers discovered six suitcases filled with crabs. Two men had 95 kilograms of crabs in their bags, while the third carried 65 kilograms in another set of three suitcases.

The arrests were made after hotel staff in Amami City noticed rustling sounds coming from the men’s unattended luggage and alerted local authorities.

Amami Oshima, part of a protected island chain south of Kyushu, is renowned for its rich biodiversity. Hermit crabs are a common sight along its beaches.

According to The Japan Times, the crabs can sell for as much as ¥20,000 (about $130) each.

Police said the hermit crabs are protected under Japanese law as “national natural monuments,” due to their ecological and cultural value. Removing or possessing them without permission is illegal.

Officials said the investigation is ongoing. “We are reviewing all possibilities,” a police spokesperson told AFP. “We don’t yet know if the crabs were intended for sale, for pets, or for food.”