The University of Queensland:

The first Professor of Physics at the University of Queensland, Professor Thomas Parnell, began an experiment in 1927 to illustrate that everyday materials can exhibit quite surprising properties. The experiment demonstrates the fluidity and high viscosity of pitch, a derivative of tar once used for waterproofing boats. At room temperature pitch feels solid – even brittle – and can easily be shattered with a blow from a hammer. It’s quite amazing then, to see that pitch at room temperature is actually fluid!

You’ve heard the term “slower than molasses”? Apparently, pitch is even slower. (thanks to @JennS79 for the link)