Scientists have uncovered the oldest known animal ancestor—a tiny, wormlike creature called Ikaria wariootia that lived 555 million years ago in what’s now South Australia. This little fossil is a big deal because it’s the earliest example of a bilaterian, an organism with a symmetrical body structure (think left and right sides, like most animals today). Its burrowing habits and simple anatomy give us a rare glimpse into how complex life first evolved.

Editor’s Note: This isn’t just about some ancient worm—it’s about rewriting the early chapters of life’s story. Ikaria wariootia helps bridge the gap between simple organisms and the vast diversity of animals that followed. For scientists, it’s like finding the "missing link" for body symmetry, a feature so fundamental that it shapes everything from insects to humans. Plus, it’s a reminder that even the tiniest fossils can hold planet-sized secrets.