Early this morning, I was walking along the beach when something enormous near the waterline stopped me in my tracks. From a distance, it looked like a huge dark log that had washed ashore overnight. But as I moved closer, the unmistakable shape of a tail and the long body behind it made me realize I was looking at a marine animal.

I kept my distance and examined it carefully. The body was massive, with a broad horizontal tail and long grooves running along its underside. Those features provided the biggest clue. Whales have horizontal tail flukes, while several species of large baleen whales also have distinctive ventral grooves along the throat and belly that expand when they feed.

The animal appeared to be a large baleen whale, most likely one of the rorqual whales—the group that includes humpback, fin, blue, minke, and sei whales. Rorquals are characterized by those expandable grooves along their undersides. Identifying the exact species from this position alone would be difficult, because specialists normally rely on several characteristics, including body proportions, coloration, dorsal-fin shape, flippers, and the appearance of the tail.

Whatever had happened, the whale had apparently washed ashore before I arrived. Seeing an animal of that size lying motionless on the sand was completely different from seeing photographs of whales swimming in the open ocean. Up close, even the tail seemed enormous, and the grooves across its body made its anatomy much easier to recognize.

So the mysterious object on the beach wasn’t debris, an unusual sea creature, or part of a boat. It was a stranded baleen whale. Finding one should be reported to local marine-wildlife or stranding authorities rather than approached or touched, because trained responders are best equipped to determine the species and what happened to it.