Sustainable Products, Projects and Green Design TetraPOT Green Sea Defence by Sheng-Hung Lee TetraPOT is a sea defence system made of concrete. It comes with plant seeds in a decomposable pot. Randomly distributed TetraPOTs along coastlines will eventually interlock to create a long-lasting sea defence of growing trees and roots that help keep the blocks in place. As plants keep growing inside out from TetraPOT, the roots intertwine and gradually form a natural sea defence. The design not only prevents soil erosion, but also helps to protect and create a natural habitat.