Answer: Packaged soil is pasteurized (steamed) before it goes to the store so I don't think you're finding snail eggs, but perlite (a volcanic substance) used for aeration of the soil. Sometimes you'll also find time release fertilizer which is round and white or light green in color, which might look like snail eggs. If you are having problems with snails or slugs, they are probably coming from other parts of the garden or the eggs or even baby snails were hiding in the soil or on any plants that you purchased. To control the snails, use an iron based bait such as Sluggo. It is harmless to wildlife, pets and people but kills slugs and snails.
Best wishes with your garden!
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