Can anyone identify this object I pulled out of the Gloucester & Sharpness canal with my magnet?

I pulled this out in two halves about 45 minutes apart from each other. The second half had numbers on it that I thought could be a date, but on further inspection of the first half it looks like the numbers continue on it, so unfortunately I don't think this was cast in 1828.

I got far more than I was expecting at this spot, given that it's on the edge of a village rather than city centre, including a still working fire extinguisher:

A car stereo amongst some other bits:

And the most nails I've ever found in a single trip by far, with the stuff I didn't find particularly interesting: