It is an icon of a skull the two bones in an x. The skull has blank eyes with a upward arrow as a nose. There are three squares for teeth. The skull is overlapping with the bones behind it.
This is a Poison 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.