Rodinia began breaking up around 850-800 million years ago and continued through about 550 million years ago. It was most likely started by a superplume of hot material rising from the mantle under the middle of the continent that began pushing pieces of it away.

Around 750-725 million years ago, magma rising into the crust was causing rifting between many pieces that became parts of new continents. As magma rose into mid-ocean ridges, it formed new crust that pushed the older crust away to both sides, moving the pieces of Rodinia farther and farther apart.

Around 650-500 million years ago, the Iapetus Ocean opened up between what became Laurentia and Gondwana. The breakup of Rodinia may have also contributed to the formation of a Snowball Earth, or a period when the earth was covered in ice, because when there are many small continents, there is more land close to the coasts than when there is one big continent, causing more of the land to experience frequent precipitation. This precipitation weathers rocks, and the chemical weathering used up carbon dioxide, reducing the amount available to act as a greenhouse gas in the atmosphere.

Rodinia began to break up during that interval, but as I understand it, the configuration of the modern landmasses that made up Rodinia is still somewhat debated. The break up gave rise to multiple ocean basins, including the Adamastor and Iapetus oceans.

Rodinia (from the Russian родить, rodit, meaning "to beget, to give birth", or родина, rodina, meaning "motherland, birthplace") was a Neoproterozoic supercontinent that assembled 1.1–0.9 billion years ago and broke up 750–633 million years ago. From Wikipedia.

It was not 'discovered' until 1970. This is the section on its "Breakup", check it out.

Ocean - about 650 million years ago "... the Iapetus Ocean formed".

There weren't any plants or animals on Rodinia, because complex life hadn't started on land yet at that time. There was multicellular life in the ocean, though, and photosynthesis had evolved about 2 billion years earlier. Thank you!