Hello Jason, this looks like the partial (? flint) infill of a burrow which has been bored by modern sea animals - possibly Piddock bivalves on the outside. It may also contain part of a fossilised sponge by the look of the section. but I am not sure about that.
So I decided to try and see what’s inside, and this is what I got. It broke across a couple of times so I’ve glued it back together.