This story was originally published on The Conversation as part of its Curious Kids series, in response to a young reader’s question. It appears here under a Creative Commons license. Wander through your backyard or walk along a stream and it’s likely you’ll see a snail: small, squishy animals with shells on their backs. Snails are found in water, whether in salty oceans, rivers, or lakes. They’re also on land: in forests, grasslands, and even your garden. As you explore your yard or woods, you can also encounter slugs, which…