Magnetic bone and wood

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Images 1 to 4 show a piece of fossil wood, this piece easily pulled a rare earth magnet.

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All of the mineralised bones shown in image 5 easily pulled a rare earth magnet. but when i attempted to do the same using a none rare earth magnet of the same shape and size, the bone did not pull the magnet.

 

My own ideas as to why the bones attract and pull the rare earth magnet, are either that the animals the bones belonged to somehow managed to absorb the magnetic material while eating, or the bones themselves absorbed the magnetic material after burial.