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.
Indeed. What is a dead give-away is that people come out and say "we found the Ark!" Real archaeologists NEVER do that. They are even extremely reticent to identify prehistoric sites with historic cultures.
The proper response to a discovery like this...if it is ever made...is to say "we found the remains of a large ship dating from such-and-such an archaeological period".
Is it the ark? We would ask.
We don't know, they'd say in all honesty. Perhaps--it matches the size, time, and place--but we can't say for sure it is the same ship.