The mystery with the platypus venom is why it evolved.

One unusual cause of focal hyperalgesia is platypus venom.

Defensin-like proteins are also a component of platypus venom.

Although not potent enough to be lethal to humans, platypus venom is nevertheless so excruciating that victims may sometimes be temporarily incapacitated.

More exotic manipulations do occur, such as racemization of L-amino acids to D-amino acids in platypus venom.