This is a drawing of some sort of object or jewel maybe. The number 20 is written right in the middle of it in a triangle, and there appear to be many many triangles all across the shape.
This is a Icosahedron icon. We've made it in iOS style
, first introduced in iOS version 7 and supported in all later releases up until now (at least iOS 11). This style is based on thin two-pixel lines and is optimized for 50x50 px. Unlike other vector icon packs that have merely hundreds of icons, this icon pack contains 13,300 icons, all in the same style and quality.