Baby turtles were once the pet of choice for small children across the United States. But in the Decade of Disco, their popularity took a hit due to concerns about salmonella. And that's when hermit crabs took off. Selling like hotcakes at coastal giftshops, they quickly spread inland. Now you can pick up supplies for the tiny crustaceans at just about any pet store.
Unfortunately, hermit crabs — like betta fish — are often bought on impulse. Before taking one home, make sure you've done your research. Here's a brief (but by no means comprehensive) introduction to their natural history and care.