Snails have shells the moment they're born, but it's kind of hard to tell. In fact, it's hard to even see a baby snail. Some are nearly microscopic, such as Angustopila psammion, whose adult-sized ...

For decades, biologists have known that hermit crabs forced to live in shells that are too small slow their growth. What wasn't clear was how they did it. New research suggests the answer isn't simply ...