Photos provided by Tim Merriman digitally processed by Jock Dempsey
This odd multi-tool anvil has an architecturally inspired conical detail that serves no purpose on an anvil but makes this a classy bit of the founder’s art. It could possibly be a cover for a bevel gear that engaged something from the back.

On the back the round hole with notches appears to be a place for a part to insert and rotate to lock or be rotated and then clamped with a bolt or screw.

Hollow interior and possible reason for conical feature.