The fossils of a giant new species of sea creature that was the "terror" of the seafloor have been discovered in South Australia.

Researchers from the University of Adelaide revealed that they have found fossils of the long-extinct trilobites on Kangaroo Island only 30 kilometers off the coast of the mainland.

Trilobites, which were notable for their armor-like exoskeletons, survived for approximately 270 million years.

The new species, named Redlichia rex by the research team, grew to around 30 centimeters (cm) in length, making it the largest species of trilobite from the Cambrian explosion -- the greatest diversification event in Earth's history -- found in Australia.

"We decided to name this new species of trilobite Redlichia rex, similar to Tyrannosaurus rex - because of its giant size, as well as its formidable legs with spines used for crushing and shredding food, which may have been other trilobites," James Holmes, the leader of the research, said in a media release on the university's website on Thursday.

"The overall size and crushing legs of Redlichia rex are a likely consequence of the arms race that occurred at this time.

"This giant trilobite was likely the terror of smaller creatures on the Cambrian seafloor."

The fossils were found in shale at Emu Bay, a world-renowned deposit where more than 100 extinct species have been discovered.

Researchers said that the preservation of trilobite "soft parts" such as the antennae and legs found in the fossils were extremely rare.

"Interestingly, trilobite specimens from the Emu Bay Shale -- including Redlichia rex -- exhibit injuries that were caused by shell-crushing predators," Diego Garcia-Bellido from the University of Adelaide and South Australian Museum said.

"There are also large specimens of fossilized poo (or coprolites) containing trilobite fragments in this fossil deposit.

"The large size of injured Redlichia rex specimens and the associated coprolites suggests that either much bigger predators were targeting Redlichia rex, such as Anomalocaris -- an even larger shrimp-like creature -- or that the new species had cannibalistic tendencies."

Specimens of the fossil will be displayed at the South Australian Museum.