Three different shapes of the fer de moline
The fer de moline, or millrind, is a common charge in European heraldry. It is called anille in modern French blazon, but the English term clearly comes from the French (fer de moulin), meaning millrind (defined by the Oxford English Dictionary as "the iron which supports the upper millstone of a corn-mill, and carries the eye which rests upon the end of the mill spindle"). From this charge comes the term Cross moline, a cross each of the arms of which terminates in two expanded and curved branches resembling the extremities of a mill-rind.
The Italian term ferro di muro hints at another interpretation of the charge, namely these fittings placed at the end of iron bars driven through walls for reinforcements.