Distribution: Texas, Florida; West Indies; Brazil. Size: 5 to 8 mm
Description: Color variable, may or may not be banded, base typically whitish-tan to reddish on fresh shells; shape turreted; sculpture of somewhat confluent, rounded axial cords crossed by numerous fine, wavy spiral threads; periphery of whorls connected by a spiral ridge, giving a knobby appearance where they intersect the axial cords; first nuclear whorls smooth; last nuclear whorl with axial riblets that give a crowned appearance; aperture elongate and U-shaped; siphonal canal abrupt; turrid notch slight. Habitat: Typically found on hard substrate. Texas offshore banks at depths from 22 to 100 m (72 to 330 ft). Depth range 1 to 100 m (3 to 330 ft). Remarks: See Ode (1992a); Williams (2005). Synonym: I. pentagonalis (Reeve, 1945).