Ediacara biota
"Cloudina" is usually found in association with microbial stromatolites, which are limited to shallow water; their isotopic composition suggests that water temperatures were relatively cool. They have also been found in normal sea-floor sediments, suggesting that they were not only restricted to dwelling on microbial mounds. On the other hand, "Cloudina" has never been found in the same layers as the soft-bodied Ediacara biota, but "Cloudina" and Ediacara biota have been found in alternating layers. This suggests that the two groups of organisms had different environmental preferences.