Yup, it's called a "drift" sinker, made to bounce along the bottom when drifting in a boat, also used for casting like any other sinker. I have a mold to make those, I used to use them in the Hudson up by Croton drifting for stripers on light tackle. A fisherman understands that there are a lot of sinker designs and most have a definite purpose to make different kinds of fishing more productive or easier to do. Right tool for the right job kind of thing. You would not want to drift fish using a pyramid sinker, they hang up too easy on rocks and other bottom obstacles, this design you found is made to not snag bottom obstacles. Obversly, you would use a pyramid sinker for still fishing in current or waves because they dig into the bottom whereas the one you found would not be so good for the job at hand.
