Digimon hatch from types of eggs which are called Digi-Eggs. In the English iterations of the franchise there is another type of Digi-Egg that can be used to digivolve, or transform, Digimon. This second type of Digi-Egg is called a Digimental in Japanese. (This type of Digi-Egg was also featured as a major object throughout season 2 as a way of Digivolution available only to certain characters at certain points throughout the season.) They age via a process called "Digivolution" which changes their appearance and increases their powers. The effect of Digivolution, however, is not permanent in the partner Digimon of the main characters in the anime, and Digimon who have digivolved will most of the time revert to their previous form after a battle or if they are too weak to continue. Some Digimon act feral. Most, however, are capable of intelligence and human speech. They are able to digivolve by the use of Digivices that their human partners have.