Submerged structures, including rubble piles, ship wrecks, oil and gas infrastructure and artificial reefs provide vertically oriented hard substrates for marine organisms in coastal waters worldwide. Sedentary filter feeders like sponges and barnacles take advantage of access to plankton in ocean currents. Their excretions support high abundances of other invertebrates and fish, while organisms beneath the structures feed on nutrients falling to the bottom, particularly after storm events. Some types of structure increase exposure to light, noise and chemical pollution and may promote the spread of invasive species.