Washington, Aug 27 (IANS): A US biologist has spotted a rare species of nautiluses, the small, distant cousins of squid and cuttlefish, after a gap of 30 years.

The creature in question is Allonautilus scrobiculatus, a species of nautilus that researchers had previously discovered off of Ndrova Island in Papua New Guinea in 1984.

Nautiluses are an ancient lineage of animal, often christened a "living fossil" because their distinctive shells appear in the fossil record over an impressive 500 million year period.

This recent sighting of Allonautilus indicates that there is still much to learn about these creatures, said University of Washington professor Peter Ward who had recently encountered the species in the South Pacific.

"Before this, two humans had seen Allonautilus scrobiculatus," Ward said.

"My colleague Bruce Saunders from Bryn Mawr College found Allonautilus first, and I saw them a few weeks later," Ward noted in a statement released by University of Washington.

Illegal fishing and "mining" operations for nautilus shells have already decimated some populations, Ward said.

This unchecked practice could threaten a lineage that has been around longer than the dinosaurs were and survived the two largest mass extinctions in Earth's history.

Allonautilus scrobiculatus is notable for the thick layer of slime and hair covering its shell.