Cypraea ovum

Cypraea ovum (commonly known as Ovum Cowrie)

Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
Superfamily:	Cypraeoidea
Family:	Cypraeidae Rafinesque, 1815

What is?
Cowries produce among the most beautiful and highly prized shells. One cowrie was even used as currency by Polynesians in the past; it is called the Money cowrie (Cypraea moneta)! However, a living cowrie is even more fascinating than an empty shell of a dead cowrie.

Where seen?

This little cowrie is commonly seen on our Northern shores usually under stones, but sometimes crawling about in the open. Sometimes also seen on our Southern shores among coral rubble.

Features:
2-3cm. Shell pear-shaped, upperside with variable patterns. It does not have spots at the front tip of the shell. Underside with 'teeth' that are tinged yellow or orange.

Marvellous mantle:

When alive and moving around, the cowrie usually encloses its shell with its mantle (a part of its body). The mantle may have a different colour and pattern from the shell and is often also 'textured' with tiny projections. When the shell is covered by the mantle, a cowrie is sometimes mistaken for a slug.

The fleshy mantle is a highly specialised organ. It is the main architect of the glossy shell, as it lays down a layer of pearl-like substances as well as the colour and patterns. It also repairs and enlarges the shell and protects it from algae and encrusting animals. This is why a cowrie shell is so shiny and smooth. When disturbed, the entire mantle retracts into the shell.

What do they eat?

As a group, cowries eat a wide variety of things from algae, sponges to scavenging and carnivorous cowries that eat other snails. Each has a radula adapted to its particular prey. Most cowries live in the intertidal zone, hiding during the day and emerging to feed at night. A cowrie has a pair of tentacles and a siphon, which is part of the mantle modified for breathing and sampling the water to look for food and mates.

Cowrie babies:

The mother cowrie lays her eggs in a horny capsule attached to a hard surface by a short stalk, these capsules are grouped in a cluster. Some mother cowries remain with their egg capsules until they hatch. The eggs are at first white and turn dark grey as they mature. Some large cowries can live for 10 years, while smaller one for 2-3 years.

Credit: http://www.wildsingapore.com/wildfacts/mollusca/gastropoda/cypraeidae/cypraeidae.htm
http://www.wildsingapore.com/wildfacts/mollusca/gastropoda/cypraeidae/ovum.htm