Segmentatidae

Segmentatidae is a family of marine gastropod molluscs, commonly known as tusk shells or scaphopods. These animals are characterized by their distinctive, elongated, tubular shell, which is open at both ends and resembles a miniature elephant's tusk. The shell is typically curved and tapers to a point. Segmentatidae shells are made of calcium carbonate and are generally white or cream-colored, though some species may exhibit other subtle hues.

The body of a segmentatid mollusc is adapted to its burrowing lifestyle. It possesses a muscular foot that it uses to anchor itself and move through sediment. Two distinct tentacles, called captacula, extend from the anterior end of the animal and are used to capture small prey, such as foraminifera and other microscopic organisms, from the surrounding sediment. These tentacles are a defining feature of the Scaphopoda class.

Segmentatids are found in marine environments worldwide, inhabiting sandy or muddy substrates from shallow coastal waters to the deep sea. They are deposit feeders, sifting through the sediment to extract their food. Reproduction in Segmentatidae is typically sexual, with external fertilization being common. The larvae are planktonic before settling to the seabed and developing into their adult form. While the shells are often found washed ashore, the living animals are more elusive due to their burrowing habits.