It is a circular net launched from the shore or a small boat but generally in shallow waters to catch the fish in the water mass or from the bottom of the water.
It has a conical shape, with weights attached to the perimeter (generally pieces of metal, lead), and when it reaches the water it behaves like a bell coming down and then tightening to the bottom, catching the fish inside the net.
It comes out of hand and no specific equipment is required.
The use of such nets requires skills and abilities.
Some shrimp species are caught with such nets.