Scientists believe they have found the oldest known animal-constructed reef on Earth, in a surprising location – the sands of the African nation of Namibia. The reef’s discovery is proof of the first animals who used hard shells as a barricade against predators.
The reef dates back to approximately 550 million years ago, during Earth’s Ediacaran Period. During this time, a large congregation of the animal Cloudina joined together to imitate a barrier of eroded rock and sand below the surface of the ocean, attaching to each other by releasing a natural cement chemical of calcium carbonate, which served as an outer shell and protective barrier for approaching predators.
The exact origins of the Cloudina are not quite known, but the structure is quite intriguing and scientists are already piecing together clues about their ancestry to more modern animals, as they were prominent in the days just before the Cambrian Explosion of biodiversity.
“It’s like a series of hollow ice-cream cones all stacked up,” biologist Rachel Wood, who works at the University of Edinburgh in Scotland, told LiveScience. “It might have been related to corals and anemones and jellyfish.”
How living creatures first developed live armor is a question explored in a study Wood co-authored this week for the journal Science. Shells and other similar hard structures came about by a process known as biomineralization, one of the indications that the Precambrian age had begun.
In addition to clues about biomineralization, it may also suggest the beginnings of social interaction among groups of more complex animals that followed.
“We have found that animals were building reefs even before the evolution of complex animal life, suggesting that there must have been selective pressures in the Precambrian Period that we have yet to understand,” Wood said in a statement.