What was the first animal on earth?

The first animals on Earth are thought to have been sponges, which are simple multicellular organisms. 

Sponge fossils show that they existed over 600 million years ago, making them one of the earliest groups of animals to have evolved. 

Sponges do not have tissues or organs and feed by filtering food particles from seawater. 

They are an important step in animal evolution because they are one of the first examples of multicellular organisms with specialized cells and a simple form of organization. 

Sponge evolution paved the way for the evolution of more complex animals such as chordates, crustaceans, and millipedes.