WASHINGTON — Life keeps popping up in the most unlikely places. In the last few days, scientists reported finding unexpected colonies of microorganisms occupying three very different regions on Earth.

According to their reports, vast numbers of invisible, one-celled creatures are:

• Sleeping but still alive after 120,000 years under almost two miles of ice in Greenland.

• Infesting thousands of miles of volcanic ridges spread across the bottom of most of the world's oceans.

• Buried in Earth's basement, a mile below a bed of 111-million-year-old mudflats off the coast of Newfoundland.

Scientists say it's important to understand microbes because they outnumber all the world's plants, animals and insects, and are responsible for many things, from climate regulation to photosynthesis, digestion and disease. Their ability to survive in the most extreme environments boosts hopes that forms of life will be found on other planets.

"Microorganisms are ubiquitous in nature," said Jennifer Loveland-Curtze, a microbiologist at Penn State University. "Microbes comprise up to one-third or more of the Earth's biomass, yet fewer than 8,000 microbes have been described out of the approximately 3 million that are presumed to exist."

In Greenland, a drilling team sponsored by the National Science Foundation discovered dormant bacteria eking out a living 1.8 miles below the island's enormous ice cap. Loveland-Curtze described the finding Tuesday at a meeting of the American Society for Microbiology in Boston.

The cells apparently survived by feeding off nutrients in tiny veins of water inside the ice. Their metabolism was barely enough to preserve their DNA, and they'd have had enough energy to divide only once in thousands of years.

Another newly discovered habitat for hardship-loving microbes is a 36,000-mile ribbon of volcanic ridges winding along the seafloor, like seams on a baseball.

According to a report in the May 29 edition of the journal Nature, billions of bacteria and their cousins archaea thrive on what look like pillows of barren lava rocks ejected from below the Earth's crust. The microbes were spotted off the Pacific coast of South America by the research submarine Alvin, which explored the wreck of the Titanic in 1986.

The discovery of an even deeper environment for life was reported in the May 23 issue of Science magazine by John Parkes, a geologist at the University of Cardiff in Wales.

Two species of heat-loving, single-celled microbes were found living at temperatures up to the boiling point in mud cores extracted by a drill ship from 111-million-year-old sediments a mile beneath the North Atlantic seafloor off the Newfoundland coast.