Tampa-based Odyssey Marine Exploration asked a three-judge panel of the 11th Circuit Court of Appeals on Tuesday to give it the rights to an estimated $500 million in coins and artifacts salvaged about four years ago.

A federal judge in Tampa ruled in 2009 that Spain is the rightful owner of the treasure from the navy frigate Nuestra Senora de las Mercedes y las Animas.

Odyssey counters that it is entitled to most of the loot because records show the vessel was on a commercial mission when it sank under fire in 1804.

A Spanish Culture Ministry official declined immediate comment.