The bristle worm is a type of segmented marine worm belonging to the class Polychaeta. These worms are commonly found in ocean environments, often living in sandy or muddy substrates. They have a long, slender body covered in bristles, or setae, which help them move and burrow. Bristle worms play an important role in the ecosystem by breaking down organic matter and serving as food for various marine animals. There are many species of bristle worms, ranging in size from a few centimeters to over a meter long. Some species are brightly colored, while others are more subdued. Although they are generally harmless, some bristle worms can deliver a painful sting if handled, due to their bristles containing irritants.