A set of pressed algae collected in Jersey and commercially produced for sale to tourists. Each specimen has been carefully labelled with its scientific name.

There has always been a thriving trade in natural objects. To this day, specialist dealers give scientists and enthusiasts access to specimens they might never be able to source directly. The sale of material has also helped to fund collecting expeditions.

Collectors are sometimes also dealers. Mary Anning, a very successful Victorian fossil collector, famously supported herself by selling her specimens, as her letter here indicates. Anning’s fame inspired the well-known tongue twister ‘She sells seashells on the seashore’.

Of course, where there’s cash to be made, there are dirty tricks to be had. Forgeries and fakes passed off as genuine specimens can extract good money from the credulous buyer. Caveat emptor.

Not all dealers were particularly scrupulous in what they sold. Some crystals have been glued on to ‘enhance’ these 19th century specimens. Such fakes are surprisingly common.