It's an exclamation point drawn inside of an equilateral triangle. The triangle is drawn with one side parallel to the ground, and the exclamation point is in the center of the triangle.
This Error icon is a responsive icon. This means that it's optimized for four resolutions, from tiny 16x16 until highly detailed 80x80. The style comes from the latest Microsoft Office
, which makes it perfect for any Windows applications, in particular, those with ribbon toolbar control. Unlike other icon packs that have merely hundreds of icons, this monster icon pack contains 16,000 icons, all in the same style and quality.