he should keep it until someone tells him the answer
<span>In order to identify and determine the type of bird that was seen, one would need to look into the North American Birds Illustrated book, wherein all the various forms of birds that exist on the continent are depicted by photos, but also explained in their actions and interactions.</span>
I would say that it should be a boulder! Hope I helped :)
In some narratives, flashbacks are used not just to provide the many useful elements already mentioned above, but to also tie together a theme.