Back in the Ediacaran Era, Cloudina developed the ability to protect themselves from predators by forming shells. These creatures, which are assumed to have been some sort of small worm by most scientists, were filter-feeders that dwelled at the bottom of the sea bed.
However, since their existence was discovered back in 2010, scientists have sought to learn more about them.
Following up on previous research, which said these tiny creatures had grown their shells as a response to the ever-increasing threat of predators, researchers at the University of Edinburgh decided to examine the Cloudina more closely.
The study indicated that the animals attached themselves to fixed surfaces, including other Cloudina, using a naturally produced cement of calcium carbonate, thus forming rigid structures. Over time, the structures formed large, animal-made reefs, one of which can be found on dry land, in Namibia, and is believed to have been built almost 550 million years ago.
Scientists are learning much more about the Ediacaran Era and its animals. It used to be believed that prior to the Cambrian Explosion–a time when many new, more advanced species suddenly appeared–that animals were mostly one-celled organisms or non-complex creatures lacking anything like circulatory systems, nervous systems, or any sort of rudimentary organs. Further study has proven evolution had progressed a bit further than they thought by then.
It is now known that primitive sponges had formed by the end of the Ediacaran Era, as well as a few other soft-bodied creatures, and maybe even some primitive form of worms, which they now speculate the Cloudina may have been. Although they know from the fossil evidence that the outer shell suggests a wormlike shape lived inside, there is no concrete evidence of what Cloudina looked like underneath the tough exterior that protected them.
Scientist are uncertain if the creatures were more like a worm, or more like coral. Either way, they are quite certain they were the forerunners of many other shelled creatures, lie the crabs mentioned here, including the ones that still exist today.
Here’s a documentary about the Cambrian Explosion so you can see what animals appeared later: