Littoraria undulata

Littoraria undulata, common name the robust shell, is a species of sea snail, a marine gastropod mollusk in the family Littorinidae, the winkles or periwinkles.

Description
Up to 2 cm, with dull brown coloration, occasionally darker on upper whorls, and with very faint pattern of wide zigzag lines (pattern fading in larger specimens).

Habitat: on rocks, mangrove trunks and drift wood.

Distribution
This species occurs in the Indo-Pacific Region and off the Philippines.