Idea of Hashtag Activity Grid Icon
There is a square that has been divided into 4 columns and 4 rows. in the lower right hand corner the square is wited out so se can not see it and the pound sign is in the whited out area
This Hashtag Activity Grid 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.