Although snails aren’t really considered to be dangerous, a new discovery reported in the journal Geology says that the ancestors of snails once had rock-hard scales and covered in spiny plates.
The 700-million-year-old fossil, discovered in 2007 but not examined until this year, is predicted to be the oldest organism discovered to have a mineral coating on its body, just like modern snails do today.
The animals were identified as part of the Characodictyon genus, and lived just before the “Snowball Earth” event 812 million years ago, which wiped out practically all life-forms with searing cold temperatures.
Using scanning electron microscopy, researchers at Harvard University and the Massachusetts Institute of Technology discovered that the fossil was covered in sharp plates that were about 20 microns wide – the width of a human hair.
Researchers speculated why a simple organism would require such a complicated exoskeleton. “It takes a lot of effort, energy and just sheer biomass to create these,” said Phoebe Cohen, a MIT researcher who took part in the research.
One assumption is that the organisms used the plates to maintain a certain level of buoyancy in the water. Modern-day plankton stay at a certain altitude in the water to maintain ideal temperature; the ancient organism may have done the same.
The scales also could’ve been used for self-defense. "It's a good possibility that these fossil plates functioned in defense against predators," said Susannah Porter, an associate professor of geological sciences at the University of California at Santa Barbara.