Armed with a walking stick, Priyadarsanan Rajan tackled a challenging 45-degree slope in the beautiful but rugged Siang Valley, within India’s northeastern state of Arunachal Pradesh. He was several miles deep in the remote Mouling National Park, traversing steep terrain while enduring relentless rain, leeches, and blood-sucking flies. Halfway up the hill, under a rock, he found a strange creature: a long, rich brown, worm-like animal with no eyes, about two dozen pairs of legs, and long antennae. Unsure of what his find was, the entomologist put the creature in…