Elongated fan-shaped, inflated, umbones near (but not at) anterior end and pink or purple (never white), thin-walled, white to purple with glossy brown periostracum adorned by soft brown strap¬like hairs (see inset), with white oblique band at center, occasionally with brown to purple radial bands, smooth; interior white to rose, occasionally purplish, margin smooth, hinge edentate. North Carolina to Florida, Bermuda, Bahamas, West Indies, Gulf of Mexico, Caribbean Central America, South America (to Brazil), also eastern Pacific. Length 55 mm (to 85 mm). Syn. tulipa Lamarck, 1819. Compare Modiolus squamosus, which has white umbones and radial bands, and trigonal periostracal hairs.

Modiolus americanus (Leach, 1815) American Horse Mussel Distribution: South Carolina to Florida, Texas to Brazil; Bermuda. Size: Adults 51 to 102 mm (2 to 4 in). Description: Color exquisite reddish-brown to pinkish-red, inner surface glossy whitish-gray with reddish-pink showing through; shape broadly oblong; sculpture of commarginal growth lines; lower margin concave at byssal gape; posterior end rounded; depression or sulcus runs from umbo to posterior end of ventral margin; shell covered with brown periostracum. Habitat: Attached to sea whip coral by byssus; or sandy-shelly bottoms at depths from 1 to 11 m (3 to 36 ft). Remarks: Easily recognized, colorful shell. See Odé (1979a); Camp et al. (1998); NOAA (2006).