Many of us leave seashells and sand behind on the beach when we travel instead of bringing them home as souvenirs. This is a great thing, since this helps preserve the natural biodiversity of coastal areas. But what about pieces of driftwood that wash up on the shore? Whether you found it on the beach or even in a gift shop, U.S. Customs and Border Protection highly discourages bringing driftwood back. In many countries (and in some parts of the United States), it’s illegal to take driftwood from protected ecosystems. But the main reason is pests may be living in the driftwood, and you could introduce a non-native species to wherever you live.