Cutting elements and bits incorporating the same

A bit comprising:

• a bit body;
• and
• a cutting element mounted on said bit body, said cutting element comprising,
• a substrate comprising a periphery and an interface surface, and
• an ultra hard material layer formed over the substrate and interfacing with said interface surface, wherein the interface surface comprises a plurality of spaced apart projections formed inwardly and spaced apart from the periphery and arranged around an annular path, wherein each projection comprises a convex upper surface defining the projection, wherein each upper surface continuously and smoothly curves in the same direction increasing and then decreasing in height as viewed in cross-section along a plane through a diameter of the substrate.