Orbitestellidae is a family of minute snails that were originally placed in tiny discoidal, low-spired-type shell families, such as Liotiidae, Skeneidae, andTornidae. Iredale (1917) recognized the orbitestellids because of their shell characters. Thiele (1929-31) placed these snails into the superfamily Trochoidea. Ponder (1967) placed the Orbitestellidae in the superfamily Rissooidea on the basis of radula and external morphological characters of the animal. Rosenberg et al. (2009) places the family under its own superfamily, Orbitestelloidea, under the subclass Heterobranchia. The shell is minute, typically less than 1 mm (1/25 inch) in diameter, usually with a flat or slightly raised spire. Shell sculpture can be smooth (Microdiscula) to elaborately sculptured (Orbitestella). Microdiscula species are either smooth or slightly sculptured with fine axial or spiral threads (Ponder and De Keyzer 1998d). Orbitestella species have spiral and intersecting axial ribs that produce a nodulose appearance. The protoconch consists of 1.3 to 1.5 whorls. The aperture is undulating or sinuate and has a distinct dorsal notch. The operculum is round and multispiral and possesses a centrally located nucleus (Ponder and De Keyzer 1998d). The head is equipped with a bilobed snout, a pair of cephalic tentacles, and eyes positioned at the center of the base of each tentacle. The reproductive system is simple and hermaphroditic and has a pallial oviduct gland, prostate gland, and an external penis positioned below the base of the right tentacle. Jaws are quite large and diagnostic for this family (Ponder and De Keyzer 1998d). The orbitestellids typically inhabit the lower littoral and sublittoral zones. Species of Orbitestella are usually found associated with rubble or under rocks, whereas species of Microdiscula are usually found associated with algae (Ponder and De Keyzer 1998d). Orbitestellids are known throughout the world, but because of their small size few are named and/or described (Ponder and De Keyzer 1998d). In Texas waters Orbitestellidae is represented by one species, Orbitestella bermudezi, whose size is about 500 to 740 µm