No , die cracks are lines , they are always raised as the metal was squeezed up thru the crack . They can be short , or long . They can circle the whole coin , or just cut a segment . Often there are more than one . Here's a Civil War Token that has the most die cracks as any I've seen . Remember this is an extreme example , and the lines are thicker than most as this die was ready to shatter very soon . On regular US coinage the dies would have been retired way before it got to this point , there is a thread ,Show Me Your Die Cracks , that will give you examples of many different kinds .
