Myterys

Myterys (ミーテリス) in Japan, is an enigmatic Mechaniloid enemy from Mega Man ZX Advent that flies near the player until they die suddenly. Because their bodies are so fragile and they die so quickly, details about them are very scarce, to the point that it's not certain that they are even Mechaniloids at all. They appear in Mysterious Lab 1 and Train 3.