One afternoon last week, while visiting his father in Seahaven, Sam Hudson came upon a prehistoric-looking creature moving across the road. It resembled a small boulder, except for its beady black eyes, puckered mouth and skin sagging into crepey pleats. Its domed shell was like petrified wood, and each hexagonal scute was a weathered sandy brown. Mr. Hudson wasn’t sure what he was looking at—wild thing or wayward pet? “My first thought was, ‘Has this creature been living out here for years and just acclimated or is he someone’s pet?’” he recalled. “It’s not every day that you see an African spurred tortoise walking up the road.” Once the lumbering chelonian made it safely out of the street, Mr. Hudson, unsure what to do, left it to amble off on its surprisingly nimble way. As it turns out, the tortoise—Turdy, a 25-year-old, 100-pound sulcata, or African spurred tortoise—had gone missing nearly 24 hours earlier. He had escaped from his enclosure at the top of Via de la Vista and made a very, very slow run for it, traveling nearly half a mile down the winding road. Turdy’s owner, Emily Peng, said her main concern during his foggy sojourn wasn’t starvation, but hypothermia. At night, he usually sleeps in an insulated alcove beneath the house, tucked inside a plastic dog shelter warmed by heat lamps and pads. The sulcata is native to the semiarid Sahel region south of the Sahara, where it burrows into the ground to find moisture and escape the heat. “Most people can’t imagine a tortoise running away,” Ms. Peng said. “But because he’s so big, if he finds something curious, he can actually move surprisingly fast.” A few hours after Mr. Hudson’s sighting, passersby recognized Turdy trundling along and called Ms. Peng. She arrived in a minivan, coaxing the escape artist with a banana peel and a soothing voice. But Turdy, low-slung and dense, required several people to heft him into the vehicle. Most people who encounter Turdy are struck by his ancient presence, a reminder of the relative newness of humankind. Nature has created millions of creatures, but most have been redrawn over time with bigger heads, weaker jaws, smaller teeth, longer legs. But tortoises—some species dating back nearly 230 million years, to the age of the dinosaurs—are a rough draft that stayed much the same. “They live for a really long time,” Ms. Peng said. “He’ll outlive all of us.”