For a two-month period, sporadic heavy downpours occurred in which the rain was red in color, often appearing like blood. The red color was due to small red particles held in suspension, initially theorized to be spores of a common lichen in India. Analysis of the isolated sediment, however, found the presence of aluminum – an element not usually found in living cells – and much lower levels of phosphorus than would be expected if the particles were biological in origin. Other theories have pointed to red dust picked up by winds crossing the Arabian peninsula and even a fine mist of blood cells produced by a meteor striking a flock of bats.
Louis argued none of these theories can explain what he's observed in the lab. Algae and fungus, which make up lichen, have DNA, Louis said, noting that his strange red "cells" do not. Further, blood cells have thin walls, unlike his microbes, and quickly die when exposed to water and air – and they are unable to replicate. Louis' particles thrive in water at temperatures approaching 600 degrees Fahrenheit – far beyond the 250 degrees known to be the upper limit for life – and they reproduce themselves. "We've already got some stunning pictures – transmission electron micrographs – of these cells sliced in the middle," astronomer Chandra Wickramasing, a scientist at Cardiff University in Wales who is attempting to replicate Louis' work, told Popular Science. "We see them budding, with little daughter cells inside the big cells."
In his journal article, Louis speculated the cell-like particles could be extraterrestrial bacteria transported to Earth on a comet or meteor that broke apart in the upper atmosphere and fell suspended in rain drops.
However, some British scientists have greater doubts to his theory, as they are also studying the strange particles:
Another British team is currently analyzing Louis' samples to confirm whether DNA is present or not. One preliminary test has returned positive. "Life as we know it must contain DNA, or it's not life," said University of Sheffield microbiologist Milton Wainwright. "But even if this organism proves to be an anomaly, the absence of DNA wouldn't necessarily mean it's extraterrestrial."