The “dolos” is an unusually-shaped concrete block of up to 30 tons, invented in East London, South Africa, in 1963, and found in millions around the world where protection from the effects of rough seas, current and tides is required, i.e. at harbour walls, breakwaters, shore earthworks. So, to protect a kilometer of coastline, about 10 000 dolosse (plural of “dolos”) are required.
The name “dolos” finds its origin in the Afrikaans word ‘dobbel osse’ (knucklebone), which is believed to refer to ox knuckle-joint bones used either in divination practices by sangomas, or to the knuckle bones game used by African children many years ago.
Dolosse can be found in the harbours of Durban, Port Elizabeth, St Francis, and many others outside South Africa such as on the Humboldt, the breakwaters of California, New Jersey, Hawaii, the High Island Reservoir East Dam in Hong Kong etc. The biggest dolosse can be found at the Ngqura deep water harbour of Port Elizabeth, where 26500 dolosse weighing each 30 tons make the upper layer of the 2.5km-long breakwater.