The debate of where life on earth originated from has been carried out for centuries. A number of theories have been suggested over the years, but the one that really keeps being thrown back and forth for consideration is by far the "we came from space" argument.

Professor Milton Wainwright and his group within the University of Sheffield department for Molecular Biology and Biotechnology believe they have now discovered some evidence which gives weight to this claim. Using a balloon (no, seriously) they have been collecting samples from the stratosphere, up to 27Km above the ground. One particular sample produced a well preserved frustule; a cell wall casing for a diatom, which is a type of algae.

This might not sound like much, but this is one of the highest recorded cases of organic matter being found in the stratosphere. Typically organic matter is hardly ever found this high up, except for the case of recently erupted volcanoes, which have been known to carry organic matter up to the stratosphere.

Since there hasn't been such an event for 3 years (you may remember the eruption of Eyjafjallajökull if you were unfortunate enough to book a holiday in early 2010), this means only one thing: it must have come from space! Or so Prof. Wainwright's group believe.

Turns out this claim is actually pretty plausible, the clean and well-preserved condition of the frustule lead the group to believe that it came from a water-based environment. It has recently been discovered that comets sometimes contain a similar body of water, and there is evidence to support that these watery cores sometimes contain the same diatoms belonging to the frustule found here. Earlier this year a paper was published describing "fossilised diatoms" found in meteorites that fell in Sri Lanka, the group confirmed that the diatoms weren't from earth using a technique called "isotope fractionation". This way they can check that the relative masses of the sample match samples of similar diatoms from earth. As you may have guessed, they didn't

The team at Sheffield plan to use the same technique to measure their sample and confirm whether or not it came from space. What could this mean for the origin of life on earth discussion? We'll have to wait and see.