Truly unparalleled navigators.

I'm not interested enough in glass to read that book, but by God, I'm glad you were.

Edit: this comment is a better answer.

Over hundreds of years, immersion in even weak acid can have an effect. Same as how splashing a bucket of water against a cliff won't do much, but given enough time, waves will scrape it away like butter.

The Galloway Hoard, a Viking-era treasure cache discovered in south-west Scotland, includes a vessel engraved with Sassanid Zoroastrian designs.

Edit: 3D image made from a scan of said vessel.