This icon is a part of a collection of Fizyka flat icons produced by Icons8. Icons follow the guidelines of iOS, Windows, and Android and are designed by a single designer, guaranteeing the consistent quality. Both PNG and vector are available.
It is an image of stylized atom. There is a small concentric circle in the middle that isn't touched by anything. Three elongated ovals form the outside, one which stands vertically and the other two form an X.