What is a sandknocker?

A sandknocker is a term used to describe a type of tool or device, typically a heavy, broad-headed hammer or mallet, used in the fishing industry, particularly for harvesting shellfish like clams. It is designed to knock on the ocean floor, dislodging shellfish from the sand or mud. The sound produced helps fishermen locate and gather the shellfish more effectively. The term can also refer to the act of using such a tool in fishing practices.