The current artificial sea defence structures tend to be dislodged over time by the force of the ocean constantly crashing against them. They have also been criticized for destroying the natural scenery along coastlines. As for natural sea defence, more than 35% of the world’s mangroves are already gone because of the greenhouse effect. Under mutual benefit theme, we will create symbiosis between artificial sea defence and natural sea defence. TetraPOT is a sea defence system that 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. It is not only a defence, but also an ecosystem. A home for other livings.