From a previous topic:
Eggs in Potting Soil.
I cooked some potting soil at 450 degrees to kill most everything in it.
I then added some Scotts Osmocote time release fertilizer pellets and distilled water and sealed.
Osmocote fertilizer is in alot of Scotts/Miracle Gro products.
After 16 days the fertilizer pellets started turning color from brown to a greenish clear color and look like some kind of insect egg.
And there you have it, home grown "Frog Eggs" LOL