An underwater cage used to propagate coral in the Maldives is offering hope for the worlds threatened reefs. The 40ft-long flower shaped structure, known as the Lotus, uses a tiny electrical current to help the sea anemone-like coral to form. Put in place eight years ago on the island of Vabbinfaru, the cage is now said to be almost invisible under the multicoloured coral which has formed on its surface. Based on an idea developed by Prof Wolf Hilbertz, a German born architect who died in 2007, and a team of marine scientists, the coral nursery was submerged at the islands Banyan Tree resort after the 1998 el nino warming phenomenon wiped out much of the local coral reefs. Through a process called mineral accretion, the low level electrical current is used to trigger a chemical reaction in the water which causes a limestone coating to form on the steel. Telegraph Surviving fragments of live coral were rescued and attached to the structure by ties while others were wedged into crevices. Tiny free-swimming coral larvae then settled on the limestone surface forming the basis of a new reef. The electrical current also provides extra energy for the corals and is said to accelerate their growth and even make them brighter in colour. Known as the rainforests of the ocean because of the diversity of species attracted to them, coral reefs are facing a major threat from climate change, pollution and aggressive fishing techniques. Last year scientists warned that up to a third of reef building coral species are vulnerable to extinction. Shiham Adam, the director of the Maldives Marine Research Centre in Male, warned that small scale projects such as the Lotus could not arrest the overall decline. Sprucing up small bits of reef can add value to a tourist resort but it certainly wont help protect the Maldives from sea level rise, he told The Guardian.