This is an iron stylus with a circular cross-section. It is pointed at one end for writing, and wedge-shaped at the other end for erasing. There are also a series of fine ridges set into the stylus to make it easier to grip. Styli were used to inscribe writing into wax-coated tablets.
This particular stylus is believed to be from the Old Jewry Excavations in London, which were undertaken in 1934. However, more than 100 styli were recovered from Walbrook Stream in London, perhaps placed there as religious offerings. At that time, people made votive objects out of the tools of their trade.