All mollusks build their own shells, whether they live in water or on land. Creatures like snails, clams, oysters and mussels use an organ called a mantle to secrete layers of calcium carbonate ...

In brief: they've grown thicker shells. The paper documents two sets of field experiments, conducted 20 years apart, measuring the thickness and plasticity in samples of tidal snails. The first ...

Some Roman emperors even passed laws forbidding anyone else from wearing purple clothing under pain of death. Billions of snail shells have been found at archaeological sites around the ...