Millions of years ago, the megalodon ruled the oceans – why did it disappear?

Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to ...
Scientific American

Freshwater mussels are disappearing—and no one is really sure why

Biologists are racing to save America’s freshwater mussels—the water-filtering keystone species that once filled the ...