Skeletal Tail

It's pretty short for a tail.
Overview
The Skeletal Tail is an Artifact that can be found in Fishing Treasure Chests, by tilling soil in The Mines or Skull Cavern, from Bone Nodes on the Ginger Island Dig Site, or as a gift from a pet dog with max friendship. It sells for 100g.
Donating a Skeletal Tail to the Museum counts toward the museum collection, and donating it together with the 

A Skeletal Tail can also be processed in the 






It is also a valid bone item for the special order “Fragments of the past,” which asks for 100 bone items gathered while the quest is active and awards money plus the Bone Mill recipe.
Official description
It's pretty short for a tail.