During the Cretaceous, 19-metre-long predatory octopuses swam the seas, and evidence from their fossilised remains suggest they may have been highly intelligent hunters

A team cracked the case by examining the fossil using a synchrotron, which produces beams of light by accelerating electrons to high speeds.

A fossil once believed to show the world’s oldest imprint of an octopus – some 300 million years old – is actually another ancient sea monster instead.

For nearly 25 years, a hand-sized fossil pulled from the rocks of Illinois held a remarkable title: the oldest known octopus on Earth. Guinness World Records listed it. Researchers cited it. It reshaped what scientists thought they knew about when eight-armed cephalopods first appeared in ancient seas.