Black Fungus

The Black Fungus is an Emblem Heartless from Kingdom Hearts. Unlike the other Mushroom Heartless, it is very aggressive. It can turn into stone to defend itself and release poisonous gases, making it very hard to defeat. If you finish them off with a critical hit at the end of a combo, they may either drop a Mystery Goo (100%), or a Mystery Mold (10%). It is possible for them to drop both, and upon being finished with a Critical Hit, they drop around 20 to 100 Munny.

Kingdom Hearts
''Hostile Heartless, unlike White Mushrooms. They attack with poison. Defeating them may bring good things, but it is not easy.''

Kingdom Hearts: Chain of Memories
An aggressive, poisonous Heartless, not to be confused with the White Mushroom.

The Black Fungus likes to paralyze its foes and toy with them.

It's tough to beat, but victory doesn't go unrewarded...

Kingdom Hearts

 * Agrabah
 * Halloween Town
 * Hollow Bastion
 * End of the World

Kingdom Hearts: Chain of Memories

 * Black Room

Hints
If you're having trouble finding Mystery Goos whenever you find a Black Fungus use Trinity Limit after getting it from The Hades Cup. After using it once, use it again on another one, after quickly using an Ether.

If you're having problems with defeating Black Fungi and you don't have Trinity Limit yet, use Gravity. It is a near-instant KO if successful.

Since the Black Fungus drop Mystery Goos after critical hits at end of combos, unequip all Combo Pluses before you fight them to shorten the length of your combo and that'll increase the chance you'll get them to drop the Goos.

In Chain of Memories and Re:Chain of Memories, defeating Black Fungi usually gives you a Calm Bounty card, so exhausting Black Fungus cards is a rather easy way to stock up on Calm Bounty cards.