"The opening of the box will definitively break the foundations of what we thought viruses were," Chantal Abergel, research director at the French National Center for Scientific Research in Marseille, told LiveScience.
The new record-breaking viruses are visible with a traditional light microscope, being a full micrometer or millionth of a meter in size, or approximately a hundredth the width of a human hair. They also each possess a whopping roughly 2,500 genes.
"We were prepared to find new viruses in the 1,000-gene range, but not to more than double that figure," Abergel said. "This really indicates than we don't know what are the possible limits anymore."
Megaviruses, which initially were mistaken for bacteria, were discovered in amoebas, and the investigators found pandoraviruses by also looking at amoebas. One virus, named Pandoravirus salinus, was unearthed at the mouth of the Tunquen River off the coast of central Chile, while the other, called Pandoravirus dulcis, dwelled at the bottom of a shallow freshwater pond near Melbourne, Australia. (Pandoravirus-like particles were actually first observed about 13 years ago, but were not recognized as viruses at the time.)