These Luccan base-silver denaros are often squarish; I have had two in my collection (one was so beat-up, I gave it away when I obtained the second) and they were both closer to square than circular.
As for whether they qualify as "crusader" or not, well, technically not (Lucca
is in north-western Italy, far away from the Crusader front lines in the Holy Land) but coin dealers are always looking for an "angle" to sell their coins; some dealers classify any coin from Europe or the Middle East struck anytime between 1100 and 1400, Christian or Islamic, as "Crusader". Both of the Luccan pieces I mentioned earlier were sold to me as "Crusader coins".
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis