The pieces of firewood that Michaela and Ben collected (clearly from the forest floor in Ben's case), without any saws or axes, are suspiciously regular (all same diameter and approximate length). Moreover, they are not enough to keep the fire going all night (which it does) and are much thinner than the logs put on the fire.
With no obvious tools like large saws, the camping group acquired large, smoothly sliced pieces of tree trunk to use as stools and narrower logs as benches.