Doesn't really smell of much to be honest.
Like asking what food salt smells like. There is a smell sure, but it's very tiny in comparison to the taste, which is very powerful.
Like the other person said licorice/aniseed yeah, maybe, if I had to put a finger on it. But MDMA crystals don't really smell. The taste would be incredibly bitter. (Which btw made me think of what it would feel like tasting mdma after using those miracle berries which make lemons sweet)