The Art of Movement is a monthly show that highlights the most significant innovations in science and technology that are helping shape our modern world.

(CNN) Usually, dumping metal into the ocean is a bad thing, but for once throwing disused items into the sea is working out for the greater good.

Over 2,500 New York subway cars have been used to create an underwater reef for crustaceans and fish in the Atlantic.

Over a period of three years, photographer Stephen Mallon of the Front Room Gallery captured images of the carriages being put in place, and his photos now are being shown in a solo exhibition in New York.

"I had read about the subway cars being dropped into the Atlantic, but I thought the project was over," said Mallon. "Then in 2007 I was scouting for another shoot and saw the barges being loaded up."

Once the subway cars had been decommissioned, they were cleaned and every part of them that could be removed -- seats, straps and wheels -- was recycled or sold. Then the carriages were stacked onto a barge, which transported them to the dropping point.

The subway cars provide a home for sea creatures.