THE METAL STONE THAT WAS USED TO MEASURE SLAVES STRENGTH IN 15TH CENTURY

 This metal device shaped like pitcher has the weight of 100kg and now it is in Old Boma Mikindani Mtwara,the device was used to test and measure the strength of slaves during slave trade in 15th century in East Africa.
The slaves were captured from different areas in the mainland(Tanganyika) and ordered to carry that device and if they were able to do so they are taken for slavery and those who failed to carry that device means they are not strong enough so they were left behind.