This is definitely not a healthy-looking mushroom. It's as black as a moonless midnight, and looking at it causes you to feel the weight of all the sorrows of the world on your shoulders.
The breeding between frozen mushrooms and spooky mushrooms will only occur when both moons become completely black. To that end, you should start the normal mushroom strategy to grow a frozen mushroom some time before Grimace is completely full (i.e. the third day of "even" months) such that your frozen and spooky mushrooms are fully grown before the time both moons are waning crescent (that is, the first Moxie day).
