“…The presence of the third dimension here allows for phenomena which are not seen in two-dimensional fractures [1]. Actual crack fronts are usually not straight lines; many step lines are found on fracture surfaces found in rock [2], glass [3,4,5,6,7], ceramics [8], rubber [9], gel [10] (including edible jelly), etc. Frechette [8] has pointed out that a crack often becomes an aggregation of crack segments which become interconnected during the course of fracture propagation and thus that such a crack front does not define a continuous line.…”