Penguins, but the egg aren't under their feet, but in a pouch. Watch the movie The March of the Penguins.
penguin
penguin
penguin
Penquins
penguin
Salamander
a platypus
platypus
The animal you are describing is the platypus. It is a unique monotreme, meaning it is one of the few mammals that lay eggs. The platypus has gills during its early developmental stages, a pouch for carrying its young, and webbed feet, which are adapted for swimming. These distinct features make it one of the most unusual mammals in the animal kingdom.
Gravity keeps your feet on the ground. It is also what keeps every living and non living thing attached to the earth.
penguins keep their eggs on their feet to keep the egg warm.if its not on their feet it might die.
Gravity.