Brine Shrimp eggs are small... and smelly too! A 'method' used to calculate the total number of small items/animals etc. is to detemine a sample as part of the whole.
In this example the total Brine Shrimp supplied fitted into a:
10cm * 10cm square
A smaller square 1cm * 1cm was placed on the larger sample.
Total numberofanimals = numberofanimalsinsmallsquare * 100
as there would be 100 1cm squares in a 10 cm square