Idea of Hot Air Balloon Icon
This looks like a hot air balloon. There's a circle, with multiple lines originating from the top and coming to a point at the bottom. At the point on the bottom, there's a small square.
This Hot Air Balloon 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.