Spider-like ancient sea monster dubbed ‘cthulhu’ discovered in UK

10 Apr 2019

A life reconstruction of Sollasina cthulhu. Image: Elissa Martin/Yale Peabody Museum of Natural History

Palaeontologists have discovered the fossilised remains of a tentacled, spider-like sea creature now named ‘cthulhu’.

An ancient creature found by a team of researchers from the US and UK would have looked like something from a horror film, and no doubt would have terrified arachnophobes.

Publishing its discovery to Proceedings of the Royal Society B, the team described a 430m-year-old creature related to modern sea cucumbers, naming it Sollasina cthulhu. Readers of HP Lovecraft will be familiar with the name given to the author’s tentacled sea monster.

This real cthulhu was quite different however, with 45 tentacle-like tube feet used to crawl along the ocean floor and capture food. In terms of size this was no giant, measuring only about the size of a large spider.

The fossilised remains of the creature were discovered in the Herefordshire Lagerstätte in the UK, a site that has proven to be a treasure trove of fossilised ancient sea animals.

“This new species belongs to an extinct group called the ophiocistioids,” said Yale University palaeontologist and co-author of the study, Derek Briggs. “With the aid of high-resolution physical-optical tomography, we describe the species in 3D, revealing internal elements of the water vascular system that were previously unknown in this group and, indeed, in nearly all fossil echinoderms.”

This reconstruction process involved grinding a fossil away layer by layer and taking photos at each of these stages. The resulting hundreds of images are then digitally reconstructed until a ‘virtual fossil’ is created.

It was through this method that the team was able to discern cthulhu’s internal water vascular system and see how it was more closely related to sea cucumbers than sea urchins. The fact it exists demonstrates that the sea cucumber skeleton was modified gradually over many, many years.

“The water vascular system operates the tentacle-like structures that they used for locomotion and food capture,” Briggs said. “The tube feet of living echinoderms are naked, but in the ophiocistioids they were plated. Our analysis strongly suggests that ophiocistioids diverged from the line leading to modern sea cucumbers.”

Colm Gorey was a senior journalist with Silicon Republic