In any poker game I ever saw:
Lammers have numbers on them such as 10, 20, 50, 100.
They are used by a floor person to mark the amount of cash they take out of the rack. They then return that same amount in chips and pick up the lammers.
Very doubtful it is a lammer.

Separators are normally clear plastic but I have seen other types of chips used.
If it was a separator there would have to have been between 10 and 12 of them in each table rack depending on the imprest amount of the bank.