[link|http://en.wikipedia.org/wiki/Aerogel|http://en.wikipedia.org/wiki/Aerogel]

To the touch, aerogels feel like a light but rigid foam, something between Styrofoam and the green floral foam used for potting artificial flowers. Despite what their name may suggest, aerogels are dry materials and do not resemble a gel in their physical properties (the name comes from the fact that they are derived from gels). Pressing softly on an aerogel typically does not leave a mark; pressing more firmly will leave a permanent dimple. Pressing firmly enough will cause a catastrophic breakdown in the sparse structure, causing it to shatter like glass--a property known as friability