[tlhIngan Hol] number of the subject implied by the {-lu'}

The suffix {-lu'} is defined as "someone or something unspecified". In english the words "someone" and "something" are singular. Or at least I think they are.. So, does this mean that whenever we use the {-lu'} it actually means that the unspecified subject is singular too ? Example: 'Impey' qach lumutlhlu'pu' Does this mean "someone (singular) constructed the pyramids" e.g. a pharaoh ? Or can it mean too "someone(s) (plural) constructed the pyramids" e.g. the egyptians ? ~ Qa'yIn