From much slandered garden snails and snails to Tool-used octopuses and mussels such as shells and oysters are molluscs among the most diverse groups of animals on the planet. But their origins are a mystery.

A newly discovered molluscover-which resembles a cut-open Durian fruit-provides indications of how the earliest species could have looked. "You were a kind of strange, spiky snail," says Luke Parry, a paleontologist at the University of Oxford, UK, who belongs to the team that described the approximately 510 million year old fossils in science on August 1st 1 .

How many other animal groups , 539 to 485 million years, and almost all of the groups found on Earth today appeared during this time.

But according to Parry, this fast pace of change makes it difficult to determine the characteristics earlier. "Only from the sight of a modern shell and a modern octopus is difficult to imagine what their common ancestor could have looked like."

The Durian fruit -like molluscase fossils, a few centimeters in diameter, were discovered on a road construction site in Kunming, China. Study mitutor Guangxu Zhang, a paleontologist at Yunnan University in Kunming, who at that time made his doctorate, thought that the first specimen he found resembled a rotting plastic bag. "It was not immediately important or noticeable," says his consultant Xiaoya Ma, a paleontologist at the University of Exeter in Penryn, UK, who is also co-author of the study.

an artistic reconstruction of Shishania Aculeata that resembles a spiky Durian fruit

But other, better preserved specimens revealed the soft underside of the being, including characteristics that can be found in modern molluscs, such as one foot. The top of the minters was covered by hollow chitin spikes - an organic compound that also forms the exoskeleton of insects. The researchers called the art Shishania Aculeata , after the renowned geologist from the province of Yunnan, Shishan Zhang, who is 87 years old today.

Hohle chitin-containing spines in early volligence such as Shishania probably gave the occasion for calcium carbonate games, which are referred to as beetles in modern mollusites. The spines also seem to share an origin with bristles containing chitin, which cover segment worms in a distant, invertebrate group called ringworms.

"This is really another piece in the puzzle," says paleobiologist Mark Sutton at Imperial College London. "It helps to help our ideas about the evolution We finally get a coherent story. ”

The spines that could also have been sensory organs probably helped Shishania and other early mollusites to avoid predators while crawling over the marbry sea floor, says Parry. "The fact that we have these fossils is pretty amazing."