Algae of this genus are made up of macroscopic filaments of cylindrical cells. The genus is characterized by its unbranched filaments, making it distinctive; its closest relatives are branching species of the genus Cladophora.
These algae are popular with aquarium hobbyists. Dumping of aquarium specimens into waterways has led to the establishment of nonnative Chaetomorpha populations, which degrades ecosystems when the algae become invasive species. Biologists recommend boiling, microwaving, freezing, or dessicating aquarium Chaetomorpha before disposing of it to avoid inadvertent releases.