Interestingly, there was an ancient Greek / Roman equivalent: amphora (pottery vases) with bumps that fit into standard cargo racks in ships. The first picture

Interestingly, there was an ancient Greek / Roman equivalent: amphora (pottery vases) with bumps that fit into standard cargo racks in ships. The first picture in the Wikipedia article is what I mean: https://en.m.wikipedia.org/wiki/Amphora https://en.m.wikipedia.org/wiki/Amphora .