What is Northwestern Seawater Carbon-Negative Material?

This Northwestern University material is produced by running an electrical current through seawater to trigger the precipitation of calcium and magnesium minerals, a process that mimics how corals and shellfish build their shells. The resulting solid binds seawater-dissolved carbon into a cement-like mineral matrix that can be used as a building material, so producing it removes more carbon dioxide from the surrounding water than the process emits.