What is a distinctive feature of cobblestones compared to flat stones?

Cobblestones are characterized by their rounded shape, which differentiates them from flat stones. This rounded geometry is essential for their traditional use in paving roads and streets, as it allows for better drainage and a more stable surface when packed together. The shape of cobblestones also contributes to their unique aesthetic when used in landscaping and historical settings.

In contrast to cobblestones, flat stones are typically used in applications that require a smooth, stable surface or structures like walls and paths where flat surfaces are preferred. The other options relate to different uses or characteristics that do not define cobblestones specifically, making rounded shape the distinctive feature that sets them apart.