[Last night dream]
Discussing with Johnrennie about dark reactions, I then brought up a paper which talked about a new model of dark matter which has a ground state lower than the ground states of most matter, and one possibility of detecting it is when some excited state relaxes into this undiscovered low ground state. The matter is predicted to be 10$^28$ kg and is said to be massive enough that if there's a calcium atom located within it, it will quickly convert into another element of this stuff.