The Grooved Ware People who built Skara Brae were primarily pastoralists who raised cattle and sheep. Childe originally believed that the inhabitants did not practice agriculture, but excavations in 1972 unearthed seed grains from a midden suggesting that barley was cultivated. Fish bones and shells are common in the middens indicating that dwellers ate seafood. Limpet shells are common and may have been fish-bait that was kept in stone boxes in the homes. The boxes were formed from thin slabs with joints carefully sealed with clay to render them waterproof.