One family in Balzan was tal-Ħobż because they ran a bakery. A family in Sliema was tal-Paddy because of an Irish ancestor nobody can now trace. People from Ħamrun are Tas-Sikkina, of the knife. People from Tarxien are Tar-Redus, of the droppings, and they have fought about it within living memory.
The “laqam” is the nickname that told you everything about a Maltese family that a surname never could. It is one of the oldest surviving pieces of Arabic culture in Malta, and it is quietly disappearing.