When I was 6 years old I became OBSESSED with micro-shells on a family beach holiday.
The sand on the beach there was amazing.
Each handful was comprised of hundreds of pretty large grains of sand a couple of millimetres wide. And for every 4 handfuls or so, there would be a micro-shell about the same size hiding in amongst them.
These shells possessed a level of detail and beauty that my 6 year old mind found fascinating.