The dried raisin, the crushed soda can, and the collapsed bicycle
inner tube exemplify the nonlinear mechanical response of naturally curved elastic surfaces with different intrinsic curvatures to a
variety of different external loads. To understand the formation
and evolution of these features in a minimal setting, we consider
a simple assay: the response of curved surfaces to point indentation. We find that for surfaces with zero or positive Gauss curvature, a common feature of the response is the appearance of
faceted structures that are organized in intricate localized patterns,
with hysteretic transitions between multiple metastable states. In
contrast, for surfaces with negative Gauss curvature the surface
deforms nonlocally along characteristic lines that extend through
the entire system. These different responses may be understood
quantitatively by using numerical simulations and classified qualitatively by using simple geometric ideas. Our ideas have implications for the behavior of small-scale structures.