Micrographs of hornet's shell
(a) Transmission electron micrograph of a hornet shell. The size scale is indicated by a vertical bar at the left which represents 10 micrometres
(b) and (c) Scanning electron micrographs of similar sections to (a) but on a scale of 1 micrometre
(d) Picture of a commercial multistage thermoelectric heat pump device (Marlow Industries Inc. Dallas, TX) with linear dimensions of a few centimetres. Note the superficial similarity in the microstructure of this device and the shell sections in (a)-(c) even though the size scale differs by a factor of 10 000 (image and text: J S Ishay et al 2003 Phys. Rev. Lett 90 218102).