Conus marmoreus Linnaeus, 1758
Marble cone, 108mm

Conus marmoreus is a common species in the Marshalls, where it lives only in the lagoon, either along interisland reefs or on lagoon pinnacles. They usually are seen at depths of 3 to 14m. In some areas, they are usually found buried in sand under rocks by day, emerging at night to feed. They seem more common exposed both day and night in and around dense patches of Halimeda algae. Although sometimes reported to eat exclusively other cone shells, we also find them eating other groups including augers (Terebridae), turbans (Turbinidae), and cowries (Cypraeidae). Immediately below, a buried Conus marmoreus emerges from the sand; possibly it detected some potential prey going by.

These are some of the specimens found in a lagoon Halimeda patch. The shell of this species is black with large, pure, bright white triangular markings. The light brown transparent periostracum makes the white look yellow.

The cone below detected the presence of a nearby mole cowry, Cypraea talpa. The cone first stretched out its siphon to smell it and see if it was acceptable prey.

When the cone decided the cowry would be edible, it extended a pale yellow tentacle from its mouth to deliver the venomous harpoon into the cowry animal. Once the cowry was stunned, the cone could then take its time eating it.

The Conus marmoreus below emerged just enough from the sand to sting and consume the animal from a Conus virgo.

This one is eating a Conus pulicarius.

Even though this cone is on the underside, it is the predator eating the animal out of the marlinspike auger, Terebra maculata.

Conus marmoreus usually attaches it egg capsules to the undersides of rocks, as below, or to clumps of Halimeda algae. Each capsule contains numerous eggs. When they hatch, they will drift with the plankton and grow a bit before settling back down to the reef to become a normal cone shell.

In the Halimeda patches, Conus marmoreus usually lays its egg capsules attached to some of the algae plants.

Here are a few more feeding records, the first on Cymatium nicobaricum. Note the freeloading hermit crabs waiting for a free meal in the photo immediately below.

Here a cone eats Terebra subulata.

Below a cone eats Cymatium nicobaricum.

This one eats a juvenile cowry.

The cone below was crawling with venomous stinger extended through a colony of Gibberulus gibbosus looking for easy prey. The strombs, however, generally detected the cone coming and would hop away.

Created 4 July 2009
Updated 14 October 2012

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