It wouldn't be outlandish to state that many a fossil collection has started with the acquisition of an ammonite. Their planispiral shells (termed a conch) are instantly recognisable and since that conch was originally composed of the relatively hard mineral aragonite, they better lend themselves to the fossilisation process.

But how much do we actually know about the animal that produces the conch? We might be able to make superficial inferences based on comparisons with the modern Nautilus, but ammonites are actually closer related to squid and octopuses.

So could you recognise an ammonite without its shell?

Prof. Christian Klug of the University of Zurich has recently described just that: a naked ammonite. In this episode, we learn about ammonite soft body anatomy and sink our teeth into the mystery of how this ammonite lost its shell.