These leathery things with bone and metal jaws are known as snapjaw homunculi — both security and entertainment, they attack anyone except their master.
Snapjaw Homunculus CR 2
Speed 20 ft., fly 50 ft. (good)
Melee bite +5 (1d6/×3 plus poison)
Space 2-1/2 ft.; Reach 0 ft.
Special Attacks dislocating jaw
During Combat The snapjaw homunculi attack intruders with their bear trap jaws. If an opponent succumbs to their poison, they switch to a new enemy.
Morale If reduced to fewer than 8 hit points, the snapjaw homunculi flee to join their master.
A snapjaw homunculus’s jaws can open very wide, giving its bite attack a ×3 critical multiplier.
Bite—injury; save Fort DC 13; frequency 1/minute for 60 minutes; effect sleep for 1 minute; cure 1 save.