The hancockiids are usually small (< 20 mm extended length). They have an elongate body shape with a long, narrow foot. The rhinophores have a tapering club with vertical lamellae and a rounded knob at the end. The rhinophoral sheaths are high, cup-shaped and edged with a number of papillae. The oral veil is represented by a rounded palm-like plate each side of the mouth bearing a number of finger-like processes. The mantle skirt is reduced to a small ridge down each side of the body from which arise up to seven pairs of large, compound cerata. Each ceratal cluster is made up of a group of individual cerata in a circular pattern attached to a common base, or rising like the fingers of a hand, the palm of which can form them variously into a cup or fan shape. These cerata are usually carried vertically but may retract or even be laid out laterally. There may be other filamentous processes arising from the body. The dorsal surface of the body, rhinophoral sheaths and cerata possess small pustules containing nematocysts. These nematocysts are used for defence, having being obtained from their hydroid prey.