"17th-Century Submersible: A Mysterious Treasure Salvager?"
Originally Published 2 years ago — by Livescience.com

A copper dome discovered near the wreck of the Santa Margarita, a Spanish treasure galleon that sank in 1622 off the coast of Florida, may actually be the remains of a 17th-century diving bell used in salvage operations. The object, previously thought to be a cauldron, matches descriptions of diving bells from that time period and was found near iron ingots that may have been used to anchor it. While there is no record of a diving bell being used on the Santa Margarita, the researchers believe it is a plausible hypothesis based on historical evidence and the size and construction of the object.