It is an image of a black paperclip. The paperclip is a solid line curved into a flat oval looped shape. The black paperclip is on a solid white background.
This Attach 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 6,000 icons, all in the same style and quality.