Imagine a world where the earliest animals were as soft and squishy as jellyfish, not the hard, spiky creatures we often picture. This is the groundbreaking revelation from a team of Bristol scientists who have rewritten the history of sponges, one of Earth’s most ancient animals. But here’s where it gets controversial: their findings challenge long-held beliefs about when and how sponges evolved, leaving scientists and enthusiasts alike scratching their heads. And this is the part most people miss—understanding this tiny creature’s past could unlock secrets about how life on Earth transformed forever.
In a study published on January 7, 2026, in Science Advances, an international team led by Dr. M. Eleonora Rossi from the University of Bristol’s School of Biological Sciences tackled a puzzling contradiction. Genetic data and chemical clues from ancient rocks suggest sponges appeared at least 650 million years ago, but their fossil record only dates back to around 543 million years. This 100-million-year gap has sparked fierce debates among researchers. Were the earlier estimates wrong, or were early sponges simply too soft to leave fossilized traces?
To solve this mystery, Dr. Rossi’s team took a two-pronged approach. First, they combined genetic data from 133 protein-coding genes with fossil evidence to create a new timeline for sponge evolution. Their findings place the origin of sponges between 600 and 615 million years ago, bridging the gap with the fossil record. Second, they delved into the evolution of sponge skeletons, discovering that the tiny glass-like needles called spicules evolved independently in different sponge groups—a revelation that flips traditional thinking on its head.
But why does this matter? Dr. Rossi explains, “Early sponges were soft-bodied, lacking the mineralized skeletons we see today. That’s why we don’t find spicules in older rocks—they simply didn’t exist yet.” This finding not only clarifies the fossil record but also raises a provocative question: if early sponges didn’t rely on spicules, what drove their evolution?
Dr. Ana Riesgo, a leading sponge expert from Madrid’s Museum of Natural Sciences, adds, “Modern sponge skeletons may look similar, but their construction is wildly different. Some use calcite, like chalk, while others use silica, essentially glass. Even their genetic blueprints differ dramatically.” To map this evolutionary journey, the team employed a Markov process—a predictive model used in finance, AI, and weather forecasting—to trace transitions between skeletal types. Their results overwhelmingly reject the idea that early sponges had mineralized skeletons, unless you assume all minerals are equal, which is unrealistic.
And here’s where it gets even more intriguing: Professor Phil Donoghue from the University of Bristol points out, “We’ve long assumed spicules were key to early sponge evolution, but our findings suggest something else entirely drove their diversification. What that was remains a tantalizing mystery.”* Could it have been environmental pressures, competition, or something we haven’t even considered yet?
Professor Davide Pisani takes it a step further, “This isn’t just about sponges. As the first reef-building animals, sponges may have laid the foundation for Earth’s earliest ecosystems. Their evolution tells us how life and our planet co-evolved, paving the way for complex life forms, including humans.”*
So, what do you think? Are we underestimating the role of soft-bodied organisms in Earth’s history? Or is there another piece of the puzzle we’re missing? Let’s debate in the comments—this conversation is far from over.
