What is this button?

I found this button in a jar of buttons I purchased at an estate auction. It is approximately 1 1/4 inches in diameter and has a Templar Cross on the front. If you look at the grooves on the front with a jewelers eyeglass it looks like there is silver in the grooves, not a lot, just a little shine. There are four holes in the center. I think it is out of shell, but I have no idea what kind and if it is old or not. If someone could help me out with this dilemma I would truly appreciate the help.
Thank you in advance,
Marta McCombs