Ancient slug fossil reveals spiky 'armor,' hints about evolution

A newly published study details a unique-looking ancient slug that had a protective 'armor' composed of small spikes. This discovery helps shed light on the evolution of mollusks, revealing that they didn't exactly have shells in the popular sense of the word, but weren't entirely without protection, either. The fossils were found several years ago by an enthusiastic collector.

The fossil dates back 478 million years, giving us a glimpse of what kind of critters scooted around in the planet's very distant past. The slug itself is spiky, something apparent from the fossil and likely used as a defense mechanism to avoid being eaten. As well, the slug is believed to have had a small single shell that looked something like a helmet.

That small 'hat' helmet sheds light on the evolution of mollusks, helping settle speculation over whether they evolved from critters with no or multiple shells. Of the seven fossils discovered, two of them are said to be complete. The slug has since been dubbed the "Calvapilosa kroegeri," a name derived in part from the creature's spikes.

Visible in the fossil is the radula, the slug's hundreds of minuscule teeth, which further indicates that it belongs in the mollusk family and isn't instead some other creature. As well, the presence of the slug's radula lay to rest debates surrounding other creatures with similar teeth arrangments, helping researchers make the determination that they, too, belong in the mollusk family.

SOURCE: LiveScience