It's a logo of a nut in the shape of an acorn. It has a shell with a cap on it as well as the stem on the top that the nut would hang from a tree from.
This Nut icon is made in Material Design style
developed by Google. This style is based on extremely simplified shapes, thin two-pixel lines, and is optimized for 24x24 px. Unlike other vector icon packs that have merely hundreds of icons, this icon pack contains 6,100 icons, all in the same style and quality.