On Friday Dr David Waterhouse presented a guest mystery object from a beach on the Norfolk coast near Cromer:

There were some interesting ideas about what it might be, ranging from oil-spill residue (Gimpy) to shark egg-case (SmallCasserole), but Henry Gee managed to correctly identify the specimen as being a molar crown from the lower jaw of the “medium sized” cave bear Ursus deningeri Richenau, 1904. Moreover, Henry also correctly identified the beds and age of the specimen- namely the “Cromer Forest-bed Formation, around 750,000 years ago”. It should probably be mentioned that Henry is a palaeontologist who at one point specialised in Pleistocene mammals and who lives in Cromer, so he did have a bit of an advantage.

The dark grey/black appearance of the object is probably part of the reason that few other people recognised it as a tooth, since we all know that fresh teeth are usually off-white, unless they are rotten. However, fossil teeth and bone are often this dark colour due to the process of permineralisation. The minerals in the original tooth are replaced by minerals in the sediment in which it is buried. I think that an iron pyrite is likely to have caused this particular colour change (although I could be wrong…).

So congratulations to Henry and a huge thanks to Dave for providing this interesting specimen – I hope there will be more in the future!