Roundworms have taken this last body plan and adapted to thousands of environments with it. From microscopic to maybe a meter long, roundworms are just what they sound like-round worms. At one end, they have a mouth, at the other, an anus, with a tube digestive system in between.
Availability of two-factor authentication for Apple ID Two-factor authentication is an extra layer of security for your Apple ID designed to ensure that you're the only person who can access your account, even if someone knows your password.
An authentication factor is a category of credential used for identity verification. For MFA, each additional factor is intended to increase the assurance that an entity involved in some kind of communication or requesting access to some system is who, or what, they are declared to be.