A marine polychaete is frolicking between gorgeous sand grains, kinda freaking me out but also pulling me straight into that curiosity spiral about everything that hides in the shifting sand. . Polychaete worms carry hundreds of tiny bristle-like structures they use to move, search for food and stay out of the jaws of anything bigger that might want to eat them. They are one of the most successful animal groups on the planet, and the fossil record shows they have been here for around half a bill