What do the angels Munkar and Nakir look like?

The two angels entrusted with questioning the deceased in their grave are Munkar and Nakir. They are black and blue. They question the deceased about the Prophet Muhammad, peace and blessings be upon him. If the person was a believer, he will answer that he is the servant of Allah and His Messenger, and his grave will be expanded for him and illuminated. But if he was a hypocrite, he will say, "I don't know," and his grave will be constricted upon him, and he will be tortured until Allah resurrects him.