Shell to 30.0 mm in length, similar in form and number of whorls to P. fenestrata; spire whorls sculptured with granulose spiral cords which number 2-4 on the penultimate whorl, body whorl with either 23-28 shallow spiral grooves, or when axial and spiral grooves are deeper, spiral cords, siphonal fasciole with 5-9 close-set, oblique cords. Aperture considerably longer than the spire, narrow and smooth within, outer lip thick and crenulate, columella calloused and with 7-9 oblique folds. Off-white in color, every second or third spiral groove lined with dark reddish-brown, primary lines thicker than intermediate ones, and with additional wavy axial lines of the same color, aperture white.

The species is similar to P. fenestrata (Lamarck) in form, but differs in features of more numerous, narrower, close-set spiral cords which are considerably lower and at times groove-like, and in a color-pattern of reddish-brown, wavy axial lines. P. undulosa replaces P. fenestrata in the Indian Ocean and the only area of overlap appear to be the Philippine Islands. In the sculptural form radula, the spiral and longitudinal grooves are deeper and form nodulose spiral cords instead of grooves.

Range - From Sri Lanka to N.W. Australia and Japan. Habitat - In clean coral and muddy sand, from the intertidal zone to a depth of 46 m.