The upper body and left leg of Joannes Baptista (named after John the Baptist) stuck out of his mobile brother, Lazarus.

He did not speak, kept his eyes closed and mouth open all the time, and was a parasitic twin.

According to a later account by Copenhagen anatomist Thomas Bartholinus, if someone pushed the breast of Joannes Baptista, he moved his hands, ears, and lips.

He also visited Danzig (Gdańsk), the Ottoman Empire, and toured Germany and Italy in 1646.

When Lazarus was not exhibiting himself, he covered his brother with his cloak to avoid unnecessary attention.