“Rapid burial is the first prerequisite for fossilization; keeps the scavengers from recycling it. Immersion is no substitute for burial, but it is a route to getting there.”

“The word “fossil” derives from the Latin “fossus” (meaning “dug up”). A fossil is defined as the preserved remains of an animal, plant or other organism and would generally infer some kind of lithification, mineralisation, chemical alteration or diagenesis. Various types of preservation processes proceed at different rates for different kinds of tissues and conditions of exposure or burial and chemical interaction. Some types of mummification (beyond simple dehydration) would also be regarded as fossilisation processes. Although most ordinary folk tend to think of fossils in millions of years of age, for palaeontologists there is a generally accepted (but completely arbitrary) cut-off date of 10,000 years. For recent fossils, the preservation may be dehydration or enrobement coupled with some level of mineralisation – even if only as a surface effect. For ancient fossils, complete mineralisation and replacement of the original organic item (or the voids within it) is more typical.” (quoted from posts 2, 4, and 12 in http://www.thefossilforum.com/index.php?/topic/32150-difference-between-fossilized-and-petrifiedand-other-stuff/ )

In view of the above, this is unlikely to be a modern bone:http://photo.xuite.net/lin440315940/10660528/22.jpg/sizes/o/