Idea of List of Thumbnails Icon
It's a logo of six square pictures arranged three on each side in two columns. To the right of each picture is a dash. The pictures are mountain, sun and flower on the left from top to bottom, and flower, cloud, mountain on the right from top to bottom.
This List of Thumbnails 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 6,200 icons, all in the same style and quality.