This is a picture of a top hat that is upside down. the opening of the hat is circular and it has a circular rim going around it. you can see a line across the center of the hat.
This Black Hat 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 5,700 icons, all in the same style and quality.