to why the people of Skara Brae left; particularly popular interpretations involve a major storm. Evan Hadingham combined evidence from found objects with the storm scenario to imagine a dramatic end to the settlement: Anna Ritchie strongly disagrees with catastrophic interpretations of the village's abandonment: The site was farther from the sea than it is today, and it is possible that Skara Brae was built adjacent to a fresh water lagoon protected by dunes. Although the visible buildings give an impression of an organic whole, it is certain that an unknown quantity of additional structures had already been lost to sea erosion before the site's rediscovery and subsequent protection by a seawall. Uncovered remains are known to exist immediately adjacent to the ancient monument in areas presently covered by fields, and others, of uncertain date, can be seen eroding out of the cliff edge a little to the south of the enclosed area. Artifacts A number of enigmatic carved stone balls have been found at the site and some are on display in the museum. Similar objects have been found throughout northern Scotland. The spiral ornamentation on some of these "balls" has been stylistically linked to objects found in the Boyne Valley in Ireland. Similar symbols have been found carved into stone lintels and bed posts. These symbols, sometimes referred to as "runic writings", have been subjected to controversial translations. For example, author Rodney Castleden suggested that "colons" found punctuating vertical and diagonal symbols may represent separations between words. Lumps of red ochre found here and at other Neolithic sites have been interpreted as evidence that body painting may have been practised. Nodules of haematite with highly polished surfaces have been found as well; the shiny surfaces suggest that the nodules were used to finish leather. Other artifacts excavated on site made of animal, fish, bird, and whalebone, whale and walrus ivory, and orca teeth included awls, needles, knives, beads, adzes, shovels, small bowls and, most remarkably, ivory pins up to long. These pins are very similar to examples found in passage graves in the Boyne Valley, another piece of evidence suggesting a linkage between the two cultures. So-called Skaill knives were commonly used tools in Skara Brae; these consist of large flakes knocked off sandstone cobbles. Skaill knives have been found throughout Orkney and Shetland. The 1972 excavations reached layers that had remained waterlogged and had preserved items that