Miracle mix looks like liquid but shatters like glass

This video - from a New Scientist article - shows the impact of a "300-gram, tungsten carbide rod into the [thin film of] oobleck" at a drastically slowed-down pace. The first thirty-six seconds of the video show 250 milliseconds of real-time action. What's important is that the impact creates a series of sharp cracks - like glass shattering - before the oobleck returns to 'liquid' and 'heals' itself.