The elephants seem to be wary of getting bitten on the soft undersides of their trunks.

BBC: Ants work with acacia trees to prevent elephant damage

Cook, without shaking or moving the scallops, until the undersides are a deep brown color.

NPR: Recipes: 'The Herbal Kitchen'

Airtrax's wheel is part of the design for a new robotic vehicle that can inspect cars' undersides to locate bombs.

FORBES: Airtrax topples the tyranny of steering.

He could detect shallower water by colour, and see the light of invisible lagoons reflected in the undersides of clouds.

ECONOMIST: Mau Piailug