There has been many debating on this in the game about the slime keys and nobody knows yet what their use are for yet neither do any announcements or updates mention these new addition to the game. It could be a possibility it is a leak and are selling for quite a hefty price of 15k each in the AH although they could be worth indefinitely more. Here will be a screenshot of the new item in the AH. Please post your thoughts and comments down below or any solid evidence on what they might be.
http://steamcommunity.com/sharedfiles/filedetails/?id=699555054
It might be most profitable if we contained our discussion of Slime Keys to a single thread, to wit:
http://forums.spiralknights.com/en/node/114889