Unusual uses of holes—With input from biology

This short review, some of it covering work not otherwise published in a peer-reviewed journal, is not meant to be exhaustive but rather to highlight some mechanical influences of holes that are apparently not much used in engineering. Apart from initiating fracture, holes can, if judiciously placed and of the right dimensions, improve the durability of a material or structure and generate information about its state of strain. By increasing the morphological complexity of the structure, they can also increase the potential for multifunctionality.