The Annelida phylum is made up of segmented worms. The most common species in the phylum are earthworms and leeches. They live mostly in sand dunes on beaches and in deserts. The majority of Annelida are hermaphroditic. They first originated on Earth during the Precambrian periods. The most common niche of Annelida is maintaining and harboring soil and sediment on the beaches and deserts they live in.