I have a general question which may sound naive: archeologists eg in Ancient Greece take a lot of information from preserved pottery they found. What physical attributes of ceramic items made of clay make them so likely to be preserved?
Two features of ceramics make them likely to be preserved.
Firstly, ceramics are fired in a kiln. This makes them solid, even as sherds. They are hard and impervious. If not mechanically disturbed (jostled, trampled, etc.) they are likely to remain in the state they were in when discarded.
Secondly, ceramics were widespread, in daily use, and regularly broken. This meant they were regularly dumped, or used as fill, or forgotten in holes. Ceramics were much like plastics in contemporary society. They were widely used and regularly discarded and replaced. As an item of common use which cycled rapidly, many ceramics were available for preservation.
Ceramics were often discarded as they were every day breakable items in wide use; and when discarded they were less likely to be destroyed if undisturbed.