Millions of tires, old washing machines, barges, warships, covering the ocean floor with thousands of square kilometers of concrete—even giant, concrete spheres full of holes: these are all things used to build artificial reefs. Advocates of artificial reefs say they are needed because they promote habitat for fish and increase biodiversity. These are indeed potential solutions to pressing problems: global oceans are faced with widespread degradation of habitat, overfishing and a loss of biodiversity. And recent legislation such as the 2022 Inflation Reduction Act has incentivized governments, industries and private foundations to explore infrastructure and technologies to make fishing and other ways we use our oceans more sustainable, according to Jacob Allgeier, University of Michigan professor of ecology and evolutionary biology.