Yes, this is very special sort of sinker. It is the less known about other end of a sea mine & is its anchor. The sinker once sunk pays out the steel cable to the prescribed length retaining the mine at its alloted depth. Many people think that mines just bob around in the sea not realising the works that keep it in place & out of sight.
In manufacture the sinkers travel along the production line on their wheels. With the mine attached the Assembly is launched from a similar railway track on the back of a mine layer.