Over the past several years, divers have retrieved thousands of objects from the wreck site of the Portuguese ship Esmeralda off the coast of Oman. The ship was originally part of an armada led by Vasco de Gama, but sank in a storm in 1503. One of the artifacts, a bronze disc measuring around seven inches in diameter, was recently confirmed to be a rare astrolabe, a type of navigational instrument. When the object was first brought to the surface it was unclear what it might be, since all lines and nautical markings had disappeared. Only two symbols remained visible—the Portuguese coat of arms and the personal emblem of King Dom Manuel I. However, 3-D laser scanning undertaken by the University of Warwick revealed 18 etched lines radiating from the disc’s center, each separated by five-degree increments. Sailors used these markings to measure the sun’s height above the horizon at noon, which helped them determine their location.

The ship that sank in 65 B.C. off the coast of the Greek island of Antikythera and that once held the famous mechanism that ancient Greeks used to plot the motion of celestial bodies has yielded intriguing new discoveries thanks to a customized metal detector put to use in the 2017 field season. The team turned up a bronze plate decorated with a bull, and an arm from a previously unknown bronze statue, which joins seven to nine other statues previously found at the underwater site. According to the project’s codirector Brendan Foley of Lund University in Sweden, who is working in cooperation with Angeliki Simosi, director of the Ephorate of Underwater Antiquities, the new finds hint that there may be even more ancient Greek artwork lying beneath the sand.

Archaeologists working with aerial and satellite technology have discovered nearly 400 stone structures in a sparsely populated region of Saudi Arabia called Harrat Khaybar, dominated by now-inactive lava mounds. They estimate that the structures, which they call gates, date to the Middle Neolithic period, roughly 7,000 years ago. David Kennedy of the University of Western Australia explains that while the landscape now appears forbidding, the area has supported human communities in periods between eruptions. “The most recent eruption, as visible from the lava flow, was quite limited in its direct impact,” he says. “People lived there before recent times.” Kennedy has not been able to determine the function of the structures from satellite images alone. “I usually look for a simple solution,” he says. “In this case I would prefer an explanation related to everyday concerns such as food and water.”