I would like to present an alternative theory as to its use.
I believe it to be a net weight designed to hold a fishing net in position on the sea bottom - while cork floats would have kept it taught floating at the top.
The reason I say this is that a sounding lead traditionally had a scooped out hole in the bottom that was filled with goose fat or similar.
The reason was that the sailor using a sounding lead needed to know not just the depth - but the type of ground for anchoring - is it sand, coral, shale, mud, etc - to know the holding characteristics for the anchor if it needed to be set. The hole on the bottom with goose fat would entrap particles like shell or grit or sand or mud in the fat, that then indicated the bottom type.
Sounding lads tended to be longer and cylindrical to sink fast and hot the bottom hard enough to compress some of the material into the goose fat for bottom ID.
If you look at marine charts - you will see shallow areas and designated anchorages that have small italicized letters that indicate the bottom type, so mariners can choose whether its a safe bottom holding characteristic, for their specific ground tackle, in whatever weather conditions they are expecting.
A sounding weight fulfills two functions and has the goose fat hole in the bottom - while a simple net weight might appear as what you have found as it only performs the one function.
Cheers