Hypothesized superocean surrounding the supercontinent Rodinia in the Neoproterozoic Era
Mirovia or Mirovoi (from Russian мировой, mirovoy, meaning "global") was a hypothesized superocean which may have been a global ocean surrounding the supercontinent Rodinia in the Neoproterozoic Era, about 1 billion to 750 million years ago. Mirovia may be essentially identical to, or the precursor of, the hypothesized Pan-African Ocean, which followed the rifting of Rodinia. The Panthalassa (proto-Pacific) Ocean developed in the Neoproterozoic Era by subduction at the expense of the global Mirovia ocean.
https://en.wikipedia.org/wiki/Mirovia