Pearlite Moon Snail (also known as the Pearly Moon Snail or Polished Moon)
Phylum: Mollusca | Class: Gastropoda | Order: Littorinimorpha | Family: Naticidae | Genus: Mammilla | Species: Mammilla simiae · Naticidae (Moon snail family) · Gastropod (Marine Snail); Globular-ovate spiral shell.
Species
Mammilla simiae
Shell Type
Gastropod (Marine Snail); Globular-ovate spiral shell.
Family
Naticidae (Moon snail family)
Size
Approximately 15-20mm in diameter based on hand scale; typically grows up to 30mm. This particular specimen appears to be a sub-adult or small adult.
Color & Pattern
Glossy base of creamy white to pale tan. It features distinct wavy or zigzag axial bands of reddish-brown. The apex is darker, and the exterior has a silky, porcelain-like sheen. The patterns are natural and well-preserved.
Rarity
Common; frequently found washed up on sandy beaches in North Queensland after high tides or storms.
Habitat
Tropical marine waters, typically found in intertidal and shallow subtidal zones. They prefer sandy substrates where they can burrow in search of prey.
Geographic Range
Indo-Pacific region, specifically ranging from East Africa to Polynesia, and very common along the Queensland coast of Australia, including the Whitsunday Islands (Hayman Island).
Description
A smooth, rounded, and attractive gastropod shell with a low spire and a large, inflated body whorl. The surface is highly polished and lacks heavy ribbing, giving it a tactile, pebble-like quality. The aperture is wide and ear-shaped, though hidden in this view.
Key Features
Smooth, glossy texture; distinct brownish 'flammules' or wavy stripes; a small but visible spire; and a characteristic dark brown or purplish callus on the columella (typical of the genus Mammilla).
Collector Value
Low monetary value ($1-$5 USD) due to its abundance, but highly desirable for decorative 'beach glass' style collections and beginner enthusiasts due to its beautiful pattern and smooth feel.
Condition Notes
Excellent beach-find condition. The gloss is mostly intact, and the patterns are vivid. No visible predator drill holes or significant calcification. Grade: Fine to Gem (beach grade).
Interesting Facts
Moon snails are predatory carnivores. They use a specialized radula to drill perfectly circular holes into the shells of bivalves and other snails to eat them. Their name 'Mammilla' refers to the nipple-like appearance of the shell's spire.
Ecological Role
Active sand-dwelling predator that helps regulate populations of small bivalves. They are in turn eaten by sea stars, crabs, and larger predatory fish. Not currently protected or endangered.
Similar Species
Mammilla melanostoma (Black-mouthed Moon Snail), which is usually larger and has a much darker, near-black columellar callus. Polinices species are also similar but often lack the wavy patterns.
Beach Finding Tips
Look along the high-tide line on sandy beaches like those on Hayman Island, especially near sandbars or areas with seagrass during low tide. They often leave 'plow' tracks in wet sand.
Notes
Australien, Hayman Island