小石

I appreciate your request, but I cannot write an accurate overview based solely on the provided context. The context consists only of an image caption ("thumb|upright=1.35|Close view of pebbles") with no substantive information about what pebbles are, their characteristics, formation, or significance. To provide an accurate 2-sentence overview, I would need to either include general knowledge or have access to a proper definition or descriptive text about pebbles, which would go beyond your instruction to base my response only on this context.

AI-generated from the Wikipedia summary — may contain errors.