Diabolical Ironclad Beetle

Black Beetle found in Los Angeles
July 8, 2010
My daughter and I saw this little guy crawling along in Descanso Gardens. As soon as we were close he stood still and we stared at him for a good long while. Once we moved on he happily kept on walking. He was not smooth and appeared to have little ridges along his back. He was not shiny but a dull black.
However you want 🙂
Los Angeles, CA

Your beetle is a Diabolical Ironclad Beetle, Phloeodes diabolicus, and you can find additional information on BugGuide.  BugGuide indicates it is found in California in “Woodlands, Found under loose bark of oak, cottonwood.”