Trying to figure out if any a fixes, and in case of a ‘yes’, then which afixes/which crystals can be used for the purpose.
As I understand this message - some crystals might work on some pets… Or?
All the best
Wack
The only crystal that can be applied to pets is calcite 
Thank you! 
Hey, could you change these kind of messages and make them more helpful?
For example, in this case:
Cannot apply crystal, only Calcite is allowed on Pets.
Not easily. All messages follow a specific pattern:
Cannot apply (insert name of item used) on this (insert targeted item type).
Creating such unique texts takes a while due to limits of game engine. (The Elements set for example required the editing of ~150 different files IIRC what the devs said)
Though I do agree that there should be a list somewhere in game.