At Georgetown University, in the United States, a researcher has shown that butterflies retain their memories from the time before the butterfly, that of the raven phase. To do this, he prepared two chambers, one of clean air and one of smelly air, so that the tobacco caterpillar could choose. When the caterpillar entered the second, it gave the animal a small electric shock, so over time the caterpillar did not enter it. Despite its conversion into a butterfly, the animal made the same option, since, according to the researcher, it remembered the discharges of the time of the crow. According to the researcher, this shows that the metamorphosis from caterpillar to butterflies is not as deep as biologists thought.