Here's why:

* Organic Limestone: Coquina is formed from the accumulation of shell fragments and other organic debris, primarily the shells of marine organisms like clams, oysters, and snails. This makes it a type of limestone.

* Deposit on Land: While coquina forms in marine environments, it can be found on land due to geological processes like uplift and erosion.

So, coquina is a type of organic limestone that is deposited on land as a result of geological events.