Olive

Thank you! That seems to answer the question indeed. So it seems that was arthropods.

I wonder what the first terrestrial animal was and how it evolves from a marine creature. What kind of land was there (does plants already lives on earth?). Note that by "animal" I mean any creature that can be considered to belong to the animal kingdom whatever it is (insects, worms, whatever...). Many answers on the web seems to mistake "animal" and "vertebrate". When did it emerge?