I is called the "Jolly Roger"
pirates
Usually a skull and cross bones or sometimes their logo .
The Jolly Roger
Pirates flying a flag showing a skull and cross-bones (Jolly Roger) was used to intimidate any ships that the pirate were going to attack.
A skull and cross-bones with the words Orlando on top and Pirates below all inside a shield shape.
The Jolly Roger
The Jolly Roger
It has a skull and bones that cross the skull.
No reference exists for a "cross bone." However, the name"Cross Bones" is used for a medieval graveyard in Southwark, London. And the term "crossbones" is used for a pair of crossed long bones (in an X style) beneath a human skull, as "skull and crossbones": an insignia used both by classical pirates and as a symbol for "poison" or "death."
If you are referring to what I think you are, those "zig zag lines" are called cross bones.
The Jolly Roger
dangercaution