Ecdysis lets you gain DNA to unlock powerful mutations, in exchange for starting over at the beginning. You can perform Ecdysis once you've reached Lv. 550. You can find the button to perform Ecdysis by scrolling down to the bottom of your "Crab" tab. Once you press this button, you will lose all your progress and gain DNA. Don't worry about the lost progress, because performing Ecdysis over and over again to gain more DNA is a crucial part of the gameplay and will let you destroy your enemies even harder and faster than before!