Projected at high speed for an unknown reason

I like this sentence in the summary from a recent paper on an unusual penetrating head injury:

We present a unique instance of a severe, high-energy, penetrating orbitocranial injury caused by a solid metallic rod that corresponded to the spray valve lever handle of a kitchen sink pre-rinse spray tap, which was fractured and projected at high speed for an unknown reason.

Link to PubMed entry for article.