Global populations have for decades migrated more and more to coastal regions. This colonization of the coast has resulted in large areas of what was formerly rocky shores, salt marshes, and mudflats becoming built environment for people. What’s more, as sea levels rise more, coastal defenses are being put in place to protect towns and cities from the oceans. These coastal defenses are also replacing natural habitats that play a vital role in the life cycle of fish, including spawning locations, nurseries, and sources of planktonic food. This, in turn, is affecting the fish stocks in the oceans. During this lesson, students will gain a basic understanding of the idea that specific habitats are essential in the lifecycle of some species. Students will work through the engineering design process to build a ‘bio-block’ solution to make sea walls a more nature-friendly solution for flood protection.