HERE ARE SOME OF THE ANSWERS:
it’s a bone for a glass dog. they were bred in the early 19th century; but short life span made it impossible to keep them viable.
A serving knife rest, so your lovely lace tablecloth will not be stained.

Congrats on keeping the comments clean everyone!
Baby dumbbell. No one likes a weak baby.
It’s a knife rest. These are not only for the carving knife, but one is at each place setting for resting the table knife after it’s used. It is NOT for the butter knife. The butter knife remains across the bread plate.

My grandmother had two. I don’t know about her background, buy she had many instruments that showed she entertained often.. I have a set of 12 salt cellars with tiny crystal spoons to sift the salt from the cellars over individual food. We used them at Thanksgiving and holiday dinners.
Today none of my children know how to “play” fancy meals.