You become an armoured, segmented, crushing, killing machine called a Trilobite. You can sense the location of food, crawl over to it, and then crush it with your heavy grinding mouthparts, called a hypostome.

It’s a successful strategy for the era, and there are many thousands of species, with specialisations for different foods, or swimming, or crawling. The biggest trilobite (that we know of so far!) is almost a metre long.

However, throughout this period, the worms and similar creatures that you eat are getting faster and better at avoiding you.

You have a long slow decline throughout the Permian era, and then, at the end of it, the massive extinction event called the Great Dying occurs. Huge volcanoes spew tonnes of carbon dioxide into the air, and every single one of you dies in the oxygen-less seas.