SOUTH PADRE ISLAND, Texas (AP) — Officials say 50 concrete pyramids have been sunk in the Gulf of Mexico off South Texas as part of an artificial reef to increase fish habitat.

The project, backed by the group Friends of RGV Reef, involves marine scientists in the state's Rio Grande Valley and elsewhere studying reefs and red snapper populations, the Brownsville Herald reported Friday.

The RGV Reef project features 3-ton (2.7-metric ton) concrete pyramids placed in the water Tuesday, about 8 miles (12 kilometers) off South Padre Island.

The structures, each up to 10 feet (3 meters) tall, were...