"Each spring," writes David Leonard in an article for Space.com, "[the Hungarians] report, 'gray fuzzy spots' appear in the bottom of the ice cover. By the middle of the first half of spring, these spots become darker, are bounded, and grow in size. By early summer defrosting, the naked dark soil of the dune is visible, and surrounded by a lighter ring. Year by year, the dark dune spots 'renew' on the same place with almost the same configuration, or 'constellation' of patches. This repeat action, the team asserts, strengthens their suggestion of fixed, biological causes of spot formation."
The Hungarian scientists conclude that this strongly suggests the life cycle of some kind of plant life.
NASA and its associated research teams don't agree with this conclusion. Their theory is that the dark spots are "the result of springtime defrosting process on Mars, not signs of biology." A somewhat less dismissive opinion from Bruce Jakosky, a Mars researcher at the University of Colorado in Boulder, states that the conclusion for Martian biology is "premature... when other, simpler processes have not been ruled out."