The videos in this blog post are not mine, they are posted from and lead back to their creator's page. I list them only for references.
I spoke with a fellow on YouTube who was playing AC 1, Altair gives Niccolo these disks that glow in the middle, he calls them "Keys".
We also see several of these "Keys" in Assassin's Creed Mirage as Basim enters the underground temple to find out the truth about himself and Nehal (which really still left me going 'heh?")
Anyway, this is the disk in question Masyaf Key:
It's after he and Roshan fight, he and Nehal will enter the chamber, and on the left and right (before the coffin thing) you'll see several disks showing on the right and the left in these chambers. Are these the same disks? The fellow speculated that they probably were not the same disks, missing the idea that precursor relics show up in these games. Even if AC 1 was made first, and mirage second, these disks are also very similar to the one's Altair gives Niccolo.
What are these "disks or keys"? Apparently, it is covered in the fandom site as:
Masyaf Key | Assassin's Creed Wiki | Fandom
The key is a precursor relic, supposedly created by the Isu and the article suggests it builds memories or shares memories with the wielder.
Could it be possible that Basim (when he was in the chamber) was trapped there and implanted with false memories of Nehal and so on?
Memory Seals | Assassin's Creed Wiki | Fandom
Is it possible also that Altair had been somewhat brainwashed also with these memory seals?
