Fossils of two prehistoric marine molluscs with distinctive spiky “hairstyles” have been discovered and named Punk and Emo.

Their strange appearance highlights the ancient diversity of molluscs – which nowadays include organisms like snails, slugs, clams and octopuses.

“Some people may be a bit down on molluscs. My partner called them loser animals. But they’re one of the really major branches of life,” says Mark Sutton at Imperial College London.

He and his colleagues unearthed the finds, which date back 430 million years, at a UK site known as the Herefordshire Lagerstätte.

The fossils, from a group of molluscs known as Aculifera, were so delicate that the researchers couldn’t just crack open the stone that contained them because that would destroy their fragile forms.

Instead, Sutton and his colleagues used X-ray scans to discern the structures inside the rock and then took thin slices of the material, photographing each layer and then putting the images together to create a 3D picture of what the organisms looked like. Both were worm-like animals about 2 centimetres long with long spines.

The music-related monikers were originally pet names, says Sutton, because the spike-laden fossils were reminiscent of hairstyles from the punk rock movement, but the names stuck, leading to the official suggestions of Punk ferox and Emo vorticaudum.

“The spikes are probably mostly protective,” says Sutton, although it is possible that they were formed because the organisms needed to get rid of the calcium that accumulated in their bodies as they went about life in the sea. Quite often, such hard protuberances may serve both purposes, he says.

The researchers aren’t sure how Punk moved, but the way a specimen of Emo is preserved in a folded position hints that it inched along a little like a caterpillar. Emo also had a bunch of stout spines at the back that point downwards and could have worked as a ratchet to aid motion, says Sutton.

These spines would have stopped it sliding backwards in the sediment as it bent, ensuring it went forwards, he says. “This inching hasn’t really been shown in any fossil at all before,” says Sutton.

“I really like the names and they definitely fit the bill for these spiky molluscs,” says Luke Parry at the University of Oxford. “Fossil molluscs that preserve soft tissues like this are incredibly rare, and so seeing what these unusual ancient animals looked like in 3D is just spectacular. This site in Herefordshire appears to be a treasure trove, like a wormy mollusc Pompeii.”

He too thinks it is likely that the spikes would have primarily been protective because both species certainly would have moved around on the sea floor rather than burrowing.

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