Small protrusions on ancient stonework, often called nubs or bosses, appear from Egypt to Peru and across the Mediterranean. In the photo below they show as small stubs standing proud of otherwise finished faces. Many explanations exist; here we hypothesize a practical, engineering origin.
In this hypothesis, the nubs may be the remnants of quarry legs: small bridges of stone intentionally left uncut to support a block during extraction. The exact cutting sequence is uncertain and likely varied, but the principle is simple: leave temporary attachments where they were most useful: two short legs under a face, a tie to the back wall, or small side bridges, then sever them at the end and lever the block free. Breaking those supports leaves small stubs, often in pairs along one edge, which can remain visible on the finished surface.
Quarry legs would have solved two problems at once: they reduced bending stresses that could crack a partly freed block, and they kept the mass safely supported until the last moment. Whether under the block, on a side, or at the back, the purpose was structural support. The remaining stubs are simply the traces left after those supports were broken away.
A practical detail explains why, when nubs are visible, they align along the lower edge of the outward face. Walls could be laid out flat in the quarry, with the future outward faces placed against the bedrock. That way the block’s original bottom face became the smooth outward face of the wall, while the exposed top followed the irregular ground. If carved as one slab of bedrock, masons could in principle cut irregular jigsaw shapes directly adjacent, which may explain the very tight fits without requiring laborious trial and error assembly later. When the first block was detached, its supports were on the worker’s side; keeping that orientation during setting naturally puts that leg edge at the bottom of the outward face. This layout to erection routine yields outward face nubs aligned along the bottom.
Why do so many ancient blocks look softly rounded at the edges, almost like cushions?
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This shape may not reflect a deliberate style, but can be understood as a natural byproduct of quarrying. If the outward face of a block was originally its underside in the quarry, workers cutting from above would strike at angles rather than perfectly horizontal, mainly for ergonomic reasons. That produces a curved or faceted edge, as can be witnessed at the unfinished Egyptian obelisk quarry.
Field evidence matches this pattern. Pyramid base stones with nubs resting on the ground make sense as quarry leg remnants rather than lifting bosses. In the Andes, many polygonal stones show two nubs near one edge, consistent with front legs. The ubiquity of nubs across cultures points to a convergent, practical solution to the same extraction problem.
In summary, nubs may best be understood as the scars of a safe, economical workflow in which quarrymen left small attachments, legs, or ties on whichever faces kept a block stable, then severed them at the end. This model explains their position, shape, and global distribution, while leaving room for later, culture specific reuse as true lifting bosses or decorative bossage.