The actual inventor of the nail is unknown, but bronze nails can be traced back to Egypt as early as 2400 BCE. As soon as humans discovered that heating iron ore could form metal, it didn't take long to shape metal into durable nails. The first evidence of nail-making occurred in Rome 2000 years ago. Large Roman fortresses had workshops where blacksmiths would craft nails that the army required.
What does durable most likely mean as it is used in this paragrpah?