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 flat color style
. This format was developed by Icons8 designer team and became immensely popular for use in web and mobile applications. Feel free to download this icon in PNG format for free, or unlock other formats for $5. Unlike other icon packs that have merely hundreds of icons, this monster icon pack contains 6,000 icons, all in the same style and quality.