The 565-Million-Year-Old Tubes That Built the First Animal Ecosystems

In the Flinders Ranges of South Australia, a 565-million-year-old bedding plane looks like a tangle of drinking straws pressed into sandstone. The tubes belong to a genus called Funisia, and they grew in dense meadows that once carpeted the Ediacaran seafloor. For decades, paleontologists treated these tubular fossils as curiosities—possible worms, maybe algae, perhaps nothing at all. But new work reveals that Funisia and its relatives built the first complex animal ecosystems on Earth, complete with competition, tiering, and community structure.

The Tube Builders

Funisia is not a single organism. The name covers a range of tubular Ediacaran fossils, typically 1 to 5 millimetres wide and up to 30 centimetres long, preserved as external molds in fine-grained sandstone. They grew upright, anchored by a basal holdfast, and stood in dense clusters like a seagrass meadow. The tubes were flexible, probably organic-walled, and appear to have collapsed and folded when buried by storm sediments.

What makes Funisia remarkable is its abundance. In the Flinders Ranges, individual bedding planes can carry hundreds of specimens per square metre. These are not isolated individuals; they are communities. The tubes grew in distinct size classes, suggesting that multiple generations coexisted on the same patch of seafloor. Juvenile tubes cluster near adults, and the spacing between individuals is regular—a pattern that implies competition for space or nutrients.

A World Before Predators

The Ediacaran seafloor was a low-energy world. There were no predators, no burrowers, no animals that moved through sediment. The substrate was bound by microbial mats—leathery films of cyanobacteria that stabilised the seafloor and prevented mixing. Into this quiet world, Funisia inserted itself as a vertical structure, rising above the mat into the water column.

The tubes grew like a forest, and like a forest, they changed everything beneath them.

By standing upright, Funisia created shade, altered water flow, and trapped organic particles. The spacing between tubes suggests they competed for suspended food—likely dissolved organic matter or small plankton. This is the earliest evidence of resource competition among macroscopic organisms. The tubes did not simply occupy space; they engineered it.

What the Tubes Tell Us

The preservation of Funisia is unusual. Most Ediacaran fossils are impressions of soft-bodied organisms that were buried alive and flattened. Funisia preserves as three-dimensional casts, because the tubes were filled with sand before the organic wall decayed. This means the tubes were hollow during life, open at the top, and likely functioned as filter-feeding structures.

If Funisia was a filter feeder, it represents a major evolutionary step. Earlier Ediacaran organisms—the fractal-like Rangea and the quilted Dickinsonia—absorbed nutrients directly through their skin. Funisia built a gut: a simple tube with one opening that drew in water and extracted food. That design—a sac with a mouth—is the body plan of virtually all modern animals.

The End of the Meadow

Funisia disappeared at the end of the Ediacaran Period, roughly 541 million years ago, along with most of the soft-bodied biota. The cause was likely the rise of burrowing animals in the early Cambrian. Burrowers churned the microbial mats that stabilised the seafloor, turning a firm substrate into soupy mud. The tubes could no longer anchor, and the meadows collapsed.

But the legacy of Funisia persists. The tiered, competitive, filter-feeding communities it built are the direct ancestors of every oyster bed, coral reef, and mussel bank that followed. The straw-like tubes of the Flinders Ranges are not a dead end. They are the first draft of an ecological architecture that life has never abandoned.