This medium to large shells are found offshore in temperate or very cold waters of the northern hemi-sphere, some at great depths. Most are dull in color and are thick and heavy, with rounded whorls and a large aperture. Usually the siphonal canal is short, broad, and recurved. Most species have spiral ribs but some are smooth or have vertical folds or ridges. Many new species are nothing more than varieties of other common and variable members of the group. Most have a thin periostracum when fresh.