Looking at the whole body of MER imagery and the rest of the data and analysis coming in, one must conclude that the majority of rocks seen on Mars surface, are one or another form of biologically several times recycled material – petrified wood, animal remains in form of the rocks and sediments etc.
Evidence for the life on Mars is mounting, and discovery by Spirit team on Sol 617 of the apparent tree fossil - and its continued exploration for more than two weeks - are bringing images that are likely to convince at least some of those who where sitting on the fence.
Here is stereo presentation of this remarkable object, likely a billion years old fossil tree.
Figure 3 is an earthly fossil tree to compare.
Let us point out some features that are important here.
We suggest, that the fragment on the right was broken off when the tree was alive, and fell off under its weight, or under the force of wind.
Left upper edge of the fragment is consistent with notion that it was formed when living tree was broken. But even more telling is the blade, chipped from the wood that has been cracked down.
It can be suggested that this combination is a signature feature of broken trees or branches. Here is a stereo image of earthly branch that has been broken for comparison, with similar blade.
All this is consistent with the MI images, which show apparent petrified wood with yearly layers.
Even more than that, they show some small fossils of the wood tenants, conceivably of times when the wood was rotting, a small light colored leaf on Figure 8, and a small plant on Figure 9.
For an earthly comparison for the petrified tree surface, one can look at Picture 10.
Now, lets say the general jest of what has been described above, is mostly correct.
This would mean that a billion years ago Mars had conditions, compatible with creation of the coal, oil, and gas deposits. Which might explain presence of methane in Martian atmosphere as a natural gas leak.
There are a number of images form different locations, which can be best described as fossilized wood.
In fact, the best explanation of the observed imagery very well could be that most of the rocks on Mars are remains of prehistoric fossilized trees. This totally reverses the paradigm - and we would have to search hard for the real rocks, instead of hunting for fossils.
A picture arises, that couple billion years ago Mars was warmer and wetter, with an atmosphere containing some oxygen. It was richly covered with thick forest, like Earth at the times when coal and oil deposits have been formed.
One year a catastrophe strikes, as the forest has grown too big and consumed a lot of water, while the Sun was extremely active - so an extreme draught occurs. The forest catches a huge fire, which consumes all the oxygen from atmosphere and suffocates all the oxygen-supported life, including all trees.
The life that has had developed since, is apparently around, but it must be able to exist without breathing oxygen.
Consequently the rocks seen now on Mars are result of the, possibly multiple, extinction recycling - which should be expected, considering how much earlier than Earth Mars must have had conditions, hospitable to life.