Yes, Roberts89, it is a piece of an antique clock. You can still see larger clock pendulum weights on Grandfather clocks made today. At 1.75" wide, yours was made for a "tabletop" or wall-mounted clock. Your pendulum weight's front is a thin shell made of stamped sheetbrass, so it would be shiny and attractive as part of the clock. The brass shell was filled with lead-alloy solder in the back, so that the pendulum would have a significant amount of weight, which helps the clock's mechanism keep time more accurately.
Regards,
Pete