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Add to this the decorative appeal, good condition and average cost of these two foot ammonites – £600-1000, and you can see why they can beat anything from Classical civilization in the same price bracket, although some people would argue that this is a high price for something that could be found beachcombing.

Nevertheless, Sotheby’s have exploited this market, which has always been strong in the US, but has only recently taken off in Britain, and the 26-lot section at the Summers Place statuary sale on 24 September was entirely sold out.

Both the ammonites illustrated here were dated to the Jurassic period (120-180 million years old), although the example on the left was smaller and sold for £650, whereas the slightly larger, 2ft 5in (74cm) high, ammonite was helped to £1300 in part by its veined marble base.

The top price of the section was paid for a nest of six Hadrosaur dinosaur eggs from the Cretaceaus period (100 million years old) which had been found in the Xixia basin of the Henan province, China, and sold at £2300.