Coast lines often need some means of protection against wave action, particularly harbour walls and breakwaters.

In 1963 the East London, South African harbour suffered severe storm damage. Two staff member of the then South African Railway and Harbour Services, Eric Mowbray Merrifield and Aubrey Kruger,  came up with an idea which would help prevent damage.  The idea became known as the Dolos which is the Afrikaans word for a knuckle bone which it was said to resemble.  Merrified was a harbor engineer and Kruger a draughts man.  In some research sources only Merrified’s name is mentioned as the designer of the Dolos but in more recent times Kruger’s name had been added.  Neither man took out a patent on the design. In later years the SAR & H Services also did not patent it.  The result was that this clever piece of engineering swept the world with its ingenuity in solving a problem.

It is interesting to note that in the 1830s when populations in South Africa were shifting  both tribal and white children played games with the dolos bones . These crude forms of childish play things could be represented as an ox or whatever imagination suggested.