Key Largo, FL (AP) – Rare twin manatees Millennium and Falcon have been released back to their home in the Florida Keys.

With satellite tracking transmitters strapped to their bodies, the two marine mammals were returned to waters leading to Florida Bay on Thursday. They were found in October 2016, after their mother was accidentally killed by a boat strike. They each weighed about 100 pounds when staff from the Keys-based Dolphin Research Center rescued and had them transferred them to the Miami Seaquarium.

They were subsequently sent to the Columbus Zoo and Aquarium in Ohio for rehabilitation before returning to the Seaquarium about two months ago. Experts say manatee calves usually stay with their mothers one to two years, adding that twin manatees make up less than four percent of all births.