This Creature Eats Stone. Sand Comes Out the Other End. (Published 2019) (2024)

Lithoredo abatanica is an organism with an unusual appetite: This creature eats stone. And when it excretes, what comes out is sand, the leftovers of a still-mysterious digestion process.

The mollusk, unearthed from the bottom of a river in the Philippines, was introduced this week by an international group of scientists in Proceedings of the Royal Society B. It is a shipworm, a group of burrowing animals related to clams, but so different from known examples that it is both a new species and genus.

Shipworms are usually known for their habit of eating wood. It’s right there in the name: They use their shells, attached to one end of their bodies, as chewing devices to burrow into and consume ship bottoms, docks and any other submerged wood. The behavior has made them the plague of mariners past and present, and in recent times, they have even sampled the delights of at least one New York City pier.

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Wood-eating shipworms fascinate scientists because they digest pulverized wood with the help of symbiotic bacteria that live in their gills. The bacteria manufacture an array of enzymes and other substances, and studying them and finding new shipworms may prove helpful in the search for new antibiotics, a subject of interest to the scientists behind the new paper.

They first heard reports of a mysterious shipworm in the Abatan River on Bohol Island some years ago, from an expedition organized by the French National Museum of Natural History. Reuben Shipway and Daniel Distel of Northeastern University, members of the Philippine Mollusk Symbiont International Collaborative Biodiversity Group, went in search of the creatures with snorkeling masks and chisels in tow.

A local resident suggested they check the bottom of the river; underwater, they spotted huge chunks of sandstone peppered with holes. Protruding from some of the rocks were the twin flags of shipworm siphons, organs that the creatures use to excrete.