In Standard Arabic, on the other hand, as any Algerian learns in primary school, it's a qalam قَلَمٌ. This, as it happens, may also be a borrowing, though a much older one; compare ancient Greek kálamos κάλαμος "reed, reed-pen", which apparently has an Indo-European etymology. Clearly, either pre-modern Algerians were so sunk in illiteracy as to have forgotten the word for a pen altogether, or they replaced a pre-existing word for pen with a French borrowing - right?
Well, no. In the Middle Ages, there weren't too many fountain pens or biros around. Classical Arabic qalam referred to something more like these:
Any Algerian who went to Qur'anic school up to the 1960s or so will remember this - a simple reed pen anyone can make using nothing more complicated than a sharp knife. (The Algerian version was a bit different than those in the picture, as it happens - usually people would use a quarter-circumference of a large reed, not the whole circumference of a small one.) More than that, they will remember what it's called: qləm قلم. There are probably people in Algeria who still use these, and very likely they still call them that.
But no one calls a modern industrial pen qləm. When industrial pens were introduced, sometime in the 19th century, ordinary Algerians ended up classing them as a new object, quite distinct from the reed pen despite its similar function, and deserving of an unrelated name. The guardians of Standard Arabic, on the other hand, decided to extend the reference of qalam to cover both. It may be no coincidence that French distinguishes calame from stylo, like Algerian Arabic, whereas English, like Standard Arabic, treats both as diferent types of pen.
Historical linguists regularly use lexical reconstruction to shed light on technological history, an approach called "Wörter und Sachen". This approach has been very fruitful in many cases. But, as this case illustrates, there are some pitfalls to watch out for: whether something counts as the same object or as a new one is a rather culture-bound question, and if investigators impose their own ideas about this on the situation they are investigating, they will get the wrong answer.