What Was That?

The workers were doing what they were ordered to do and when it comes to finishing a job these workers don’t usually give it much thought and try to complete the work as soon as possible. But this time the workers had to stop because it was something really strange that took them by surprise and they wouldn’t have thought that something this valuable was lurking on this site for god knows how many centuries. So, the workers notified the higher authorities because this was something out of their reach.