Strange, soft primordial organisms that lived more than half a billion years ago thrived with a little help from their friends — providing one of the oldest examples of one living thing reaping benefits from another.

The first complex life forms big enough to be seen with the unaided eye emerged more than 540 million years ago, during the Ediacaran period. To understand these odd organisms’ diets, Brandt Gibson at Vanderbilt University in Nashville, Tennessee, and his colleagues modelled the flow of water around Ernietta plateauensis, a cauldron-shaped Ediacaran life form. The researchers found that fluid that flows towards an Ernietta tends to circulate inside the organism’s hollow, as would be expected if Ernietta filtered its food from the water.

In simulations of a tight clump of Ernietta, organisms that were downstream of their neighbours enjoyed especially turbulent flows of liquid, which probably supplied rich doses of food. This may explain why Ernietta fossils are usually found in groups of 5-15 individuals.