Removing otoliths (ear bones) from a fish head:  a short video.

Otoliths are used to determine how old a fish is.  This is because otoliths grow in rings.  Much like a tree, a fish adds one ring of bone to its otoliths each year.  So if you count the rings, you know how old the fish was in years.

Using mosquito netting to create improvised histology cassettes.