Another What was this used for item

[archer]

This one weighs 16 pounds has a 7/8 inch bore no pan so likely fired by a fuse.
Odd shapes but no indications of how it might have been attached.

[Rich]

I would think it was the mortar of it's time.
Rich

[BBJW]

Just a type of signal gun. Not a weapon.-- bbjw

[Richard G]

Maybe some form of fireworks mortar?
Regards
Richard

[BBJW]

A type of 'thunder mug' naval signal device. Not a usual design tho.- bbjw