Seven giant funeral urns dating to pre-Columbian times have been found deep in the Brazilian Amazon rainforest. A fisher who works in this little-known waterlogged area of the middle Solimões region, along the upper course of the Amazon River, made the discovery after a 50-foot-tall (15 meters) Paricarana tree fell over, revealing the urns buried beneath it.

The age of the urns is currently unknown; being Pre-Columbian, they’re either centuries or millennia old. But their burial place — a human-made island — is extraordinary, although it’s unknown if the culture that created the islands also crafted the urns, according to archaeologists at the Mamirauá Institute for Sustainable Development (IDSM) in Brazil.

Two of the larger ceramic urns — which measure up to 35 inches (89 centimeters) in diameter — contained human bones, while the others held a mixture of seeds and the remains of fish, frogs and turtles, said Geórgea Layla Holanda, an archaeologist at the IDSM who co-led the excavation. These seed and animal remains were likely part of the funeral ritual.