The three suspects – Liao Zhibin, 24, Song Zhenhao, 26, and Guo Jiawei, 27 – were found to have 160 kilograms of the live crustaceans in their possession on Wednesday, according to police on the Amami Islands, near Okinawa.

Police said a hotel worker in Amami, a city on the island of Amami Oshima, alerted environmental authorities after spotting something suspicious about the suitcases the three men had asked hotel staff to watch.

“They heard rustling sounds coming from a suitcase that was being held in storage,” a police officer told CNN.

Officers later arrived at the hotel and found the spiral-shelled hermit crabs stuffed into six suitcases, according to police.

When they returned to the hotel on Wednesday, the three men were arrested for possessing the crustaceans without proper authorisation, Kyodo News reported.

It’s unknown why the three men were transporting the crustaceans.

Police did not provide more detail on the exact species, but told CNN Friday that the hermit crabs seized are classified as “national natural monuments” in Japan because of their cultural and scientific value, and protected under Japanese law.

The Amami archipelago, off south-western Kyushu and just north of Okinawa, is a popular tourist destination and known to be home to a diverse array of native plants and animals.