This is a speech bubble in the shape of a rounded rectangle. There is a small curved point sticking out of the bottom of the bubble and coming from the left.
This is a Comments 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 13,700 icons, all in the same style and quality.