Bioturbators include organisms that contribute to the rearrangement and aeration of marine sediments. The process of bioturbation most often occurs when benthic organisms burrow and interact with soft-bottom substrate. The distillation of these sediments provides oxygen to the benthic ecosystem. Infaunal and epifaunal contact with the seafloor is a significant reason why marine sediment is semi-organized in terms of size and uniformity. In addition to sifting through the marine substrate, many organisms consume and digest sediment particles, which along with providing nutrients to the soil, creates a more oxidized environment for other living organisms that otherwise could not survive in anoxic sediments. Marine organisms such as Bivalves and Polycheata are well known for playing a major role in the process of marine bioturbation. Due to the vast spread of polycheata throughout the ocean, these organisms are excellent candidates for research concerning the overall heath of the benthic ecosystem, as their absence may be indicative of detrimental conditions within the substrate.