From the Super Mario Wiki
Dark Growmebas are pitch black, shady Growmebas found in rooms 35 and 37 of the Flopside Pit of 100 Trials, in Super Paper Mario. They look like floating, dripping black squares. Like all Growmeba subspecies, they multiply rapidly and create many clones of themselves. However, they are much more difficult to defeat as the true enemy looks exactly like its clones. It would be recommended to defeat the true Growmeba before it can multiply, otherwise the player would have to defeat them all through trial and error.
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