"Moonrocks" is a slang term that you could argue has no precise definition for the quality/legitimacy of the product. There are hundreds of MDMA "like" drugs such as the aforementioned Methylone. Some of which include, MDA, 6-APB, Ethylone, Butylone, MBDB, MDEA, 4-MMC, 4-BMC, ect. ect. That being said if your accustomed to getting legitimate MDMA powder and not inhaling crappy ecstasy pills by the hand full you'll be able to notice the distinguishable differences between each above mentioned compound's effects on the body and that of pure MDMA's. My friend went to the most recent "Basscenter" and said it was one of the greatest times of his life, with plenty of legitimate drugs floating around. Though the only way to be absolutely certain of what you have is to buy a Marquis reagent test and visually gauge the reaction it has on the purported MDMA.