The Old Burial Ground is getting a makeover, piece by piece. "The 884 stones in here take a lot of work," said Mike Walker, the city's assistant director of engineering and operations.

The look of Sea Stone varies depending on the sizes and quantities of shells and binders used "The power of the material is different," explained Hyein Choi, co-founder of Newtab-22, told Dezeen.

However, archaeologists have found lots of stone artifacts with ground edges dating as far back as 60,000 to 30,000 years ago. But it's unclear how those tools might have been used.