Fibula were used to fasten togas and chiton, more or less a large safety-pin (the back pin is missing). This one is made of lead; it is so incredibly rare that the largest collection of fibula on the planet does not have one! Most fibula are made of bronze, silver and gold.
Found in Bari, Italy, this is among the rarest antiquities you will ever see on the open market. Compare with Antiquities of Roman Britain, Fig. 10, 329, Hattatt; length is 114mm, around 4".
If you remember pinning this baby onto your toga, it might be a good time to get the fibula back and perhaps consider wearing a toga around the house.
Extremely collectible, but the real point is that if you got a tingle from the photo, it could be a powerful link to your distant past!