Sinustrombus sinuatus

The laciniate conch, Sinustrombus sinuatus, is a marine gastropod mollusk belonging to the true conch family, Strombidae. Its range covers the tropical Indo-Pacific region. The shell is thick and solid, featuring a large body whorl. While it can reach a maximum length of 13 cm, specimens around 10 cm are more typical.

The short spire is composed of roughly twelve whorls. Externally, the shell is white with blotches or spots of yellow, orange, or light tan; internally, it is brown, purple, or pink. The species shows considerable variation in shape, particularly in the lip of the aperture, which bears several blunt, finger-like projections.

These processes can range from barely visible to very prominent. In fact, the differences among these shell forms are greater than the differences between this species and its relatives Lambis millepeda, Lambis scorpius, and Lambis lambis, which it resembles. S. sinuatus inhabits tropical and subtropical waters from Sri Lanka and eastern India across to the Philippines, Japan, Taiwan, Indonesia, Melanesia, Papua New Guinea, and northern Australia.

It lives on sandy substrates mixed with algae and coral fragments in areas of low turbidity, from the low intertidal zone down to about 20 meters in depth. Contrary to a 19th-century belief that strombids were carnivorous, S. sinuatus feeds on fragments of algae, ingesting sand and detritus and obtaining nutrition from decomposing organic material. It is an active mollusk, using its slender foot and robust operculum to flip itself off the seabed for locomotion or defense. The operculum and the finger-like processes on the shell lip are also employed in righting itself when overturned.