Erizo

A hedgehog. A small, spiny mammal sometimes kept as a pet. Generally depicted in full profile on all fours facing left, with a round, brown body covered with spines and a light-brown face and underside.

Sometimes used to represent a porcupine or echidna.

Twitter's design has always been a hedgehog facing forward. Google's design originally featured a hedgehog facing forward, though it was changed to full profile with Android 11.0. Facebook’s design previously featured a hedgehog on its back, rolled up in a ball.