This is a Load 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 12,100 icons, all in the same style and quality.
The image is a circle made of circles. The circles vary in size. Starting from the bottom left is the smallest circle that looks like a dot. Going clockwise, the circles get bigger until the biggest one is right next to the dot at the bottom.