One of the world's rarest creatures has been spotted for the third time by a team of US biologists. Allonautilus scrobiculatus before the recent sighting was seen only two time, which makes them one of the planet's most elusive and unknown inhabitants.

As per experts, this creature is said to have survived nearly two ice ages and pre-date dinosaurs. It has only been see by two people in the world.

Peter Ward, a professor of biology at the University of Washington in the US, was the first person to spot this rare creature. Ward first saw Allonautilus scrobiculatus in 1984.

Allonautilus scrobiculatus is a species of nautilus, distant cousins of squid and cuttlefish, they have been christened the 'living fossils' of the oceans' waters due to the distinctive shells that appear as fossils over a 500-million-year period.

Mr Ward said he again returned to Papua New Guinea in July of this year to study Nautilus. The tea this time used 'bait on a stick' systems to tempt the creatures into view almost 500 and 1,300 meters below the water's surface.

Biologists said in a statement that this creature needs a delicate balance to survive. It could not survive in too hot water and the place where they perish should exceed 2,500m in depth.

Biologists believe as a result populations near one island or coral reef will differ dramatically. But the animals are threatened by extinction, illegal fishing and mining operations are major causes of threat.

Mr Ward, said, "As it stands now, nautilus mining could cause nautiluses to go extinct. This could be the rarest animal in the world. We need to know if Allonautilus is anywhere else, and we won't know until we go out there and look".