Earth's oceans naturally pull carbon from the atmosphere and store it deep within the ocean waters. The deeper a particle sinks, the better, because the carbon will take a longer time to return to the surface and into the atmosphere. Researchers previously believed the transfer of particles from the surface to the deep ocean occurred simply due to gravity (the gravity pump). Weber and his colleagues found that other processes are important in transferring carbon to the deep ocean, including ocean mixing and transport via animals such as small fish (the migrant pump). The researchers refer to these processes collectively as "particle injection pumps" because they can "inject" particles at much deeper depths before the carbon is released.