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Phylum Mollusca > Class Gastropoda > Family Naticidae
Ball moon snail
Neverita didyma
Family Naticidae
updated Aug 2020

Where seen? This almost spherical moon snail is commonly seen on a few of our sandy Northern shores. Especially at night or on a cool day, usually busy ploughing through the sand in search of prey, near seagrass areas. Elsewhere, it is found in sandy to muddy bottoms. It was previously known as Polinices didyma.

Features: 3-5cm. Shell smooth glossy, thick heavy, spherical, the spiral tip not sticking out so that the overall shape resembles a ball (Didyma means 'testicles'). Shell pattern usually plain white sometimes with pearly pastel shades, with narrow white spiral at the spire, sometimes with irregular blotches of darker colours. On the underside, a brown blotch and a small depression. Operculum smooth, made of a thin horn-like material, yellow. Body huge, plain white. Tentacles with more opaque white bands.

Sometimes mistaken for the Oval moon snail that is easily distinguished by its more tear-drop shaped shell which on the underside is completely white (no brown patch) and has a bump instead of a depression. The Ball moon snail is less shy and doesn't immediately retract completely into its shell the way the Oval moon snail does.

Tanah Merah, Feb 07

Tanah Merah, Feb 07

Changi, May 11

Siphon (upper left) and tentcles
What does it eat? This snail is often seen actively hunting Button snails.

Human uses: It is collected as food and for the shell trade. In Thailand it is commonly collected using fishing nets at depths of 2-10m.

Ball moon snails on Singapore shores
On wildsingapore flickr

Other sightings on Singapore shores



  • Tan Siong Kiat and Henrietta P. M. Woo, 2010 Preliminary Checklist of The Molluscs of Singapore (pdf), Raffles Museum of Biodiversity Research, National University of Singapore.
  • Tan, K. S. & L. M. Chou, 2000. A Guide to the Common Seashells of Singapore. Singapore Science Centre. 160 pp.
  • Abbott, R. Tucker, 1991. Seashells of South East Asia. Graham Brash, Singapore. 145 pp.
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