They did:
Even more intriguing, some of the wood-like rocks were tested just this week and actually proved to be petrified wood . . .
Ah, but this is a mere assertion. Where are the micrographs that show cellular structures as found in genuine petrified wood? In view of the fact that the pictures show commonplace weathered shale, complete with color variations on the surface due to mineral oxidation, that is so similar to hundreds or thousands of similar outcrops, the burden of proof lies squarely on the shoulders of the ark proponents.