5,000-year-old stone tomb discovered in Spain is 43 feet long — and it holds many prehistoric burials

Archaeologists in Spain have discovered a 5,000-year-old stone monument that holds multiple burials and many grave goods, including weapons.

These prehistoric stone monuments, known as dolmens, are often found in European countries like Spain, France and the U.K., such as the 5,700-year-old Arthur's Stone in England, and they typically have stone walls and a large stone roof.

The newfound dolmen, unearthed in Spain's southern autonomous region of Andalusia, is "one of the most monumental and best-preserved funerary structures in Andalusia," researchers said in a translated statement.

The newly discovered dolmen is 43 feet (13 meters) long, and its walls are made of 6.6-foot-high (2 m) vertical stone slabs known as orthostats.

"The entire dolmen was also covered by horizontal large stone slabs, and on top of this covering, there was a tumulus [a human-made mound] of sand and small stones" Eduardo Vijande Vila, an associate professor of prehistory at the University of Cádiz and co-director of the excavations, told Live Science in an email.

The stone monument was found near the town of Teba and was gradually excavated over four excavation seasons, according to the statement. Several ossuaries (small graves that contain human bones) were found, meaning that this dolmen was used as a "collective burial" for multiple individuals, Vijande Vila said. Grave goods were found alongside them and include seashells, ivory pieces, arrowheads and a halberd, which is a weapon that is shaped like a spear with an ax at the end of it.

The seashells found by the team hint at trade, the team noted. "The presence of seashells in an inland area reflects the importance of the sea as an element of prestige and the existence of long-distance exchange networks," Juan Jesús Cantillo, a prehistory professor at the University of Cádiz, said in the statement.

Dolmens were used at various times around much of the world and often served as tombs. They may have had other uses, such as for rituals or habitation, and were sometimes aligned with solar events, such as the summer solstice. Vijande Vila noted that dolmens may have also served as territorial markers and may have signified land ownership — an important designation in agricultural societies.

Spain has a vast number of prehistoric dolmens. One famous example is the 7,000-year-old Dolmen of Guadalperal, which has about 150 standing stones and may have been used for rituals. Today, it is underwater, but it occasionally appears during times of drought.

Research into the newfound dolmen and its remains is ongoing.