Loop half of a key

There are two key halves. The bottom part is called the Loop Half while the top is called the Teeth Half. They're dropped from any monster that drops gems, though they're much more rare. They can also be given to you by the Captain Arnav, Mysterious Old Man or Miles, Giles, or Niles, or found in the chest opened with the Crystal key. When you have each half, you can combine them to make a Crystal key. It appears that the tooth half is dropped by higher level monsters while the loop half is dropped by the lower leveled monsters, teeth are generally higher in price.