The Daring Dufas wrote:

I don't think it any more odd than the blocks of wood some of my
Jewish cousins may wear on their forehead...

They're not blocks of wood (they're sometimes called phylacteries). They're
leather and contain scrolls of parchment. Written on these pieces of
parchment are four biblical passages. These boxes are donned on the forehead
and left arm during morning prayers to fullfill the commandment:

"And it shall be for a sign for you upon your hand, and for a memorial
between your eyes, that the law of the LORD may be in your mouth; for with a
strong hand did the LORD bring you out of Egypt." Exodus 13:9.

I don't know of any other religious regalia that can be traced to a biblical
command.