A 60-ton, 40,500-year-old log unearthed during an excavation in New Zealand may hold clues to one of earth’s great ancient mysteries, the New Zealand Herald reports.

The massive log, once a kauri tree (Agathis australis), was preserved in clay nearly 30 feet underground before it was excavated by a power company in March 2019 in Ngāwhā Springs in the Northland region of New Zealand. Researchers said the size of the ancient tree indicates it was 1,500–2,000 years old when it died.

Due to its age, scientists said the log could aid in answering long-held questions about the Laschamp Event, when Earth’s north and south magnetic poles reversed roughly 41,000 years ago.

“So this tree is critical, we’ve never found one of this age before,” one scientist told the Herald.

The power company, Top Energy NZ, gifted the ancient kauri log to a local indigenous community.