Dead holly from snails, how do i get rid of them?

Our holly shrub died from the center out primarily to one side. When replacing the shrud, we found small spheres approximately 1/8 in diameter that looked like eggs. They were grayish in color, and there was hundereds of them mixed into the soil in...

this particular side of the shrub about foot or so deep. The eggs were on the side of the shrub that looked the worst.
I was told by a friend that these snail egg, and that is what killed our shrub.
Does this sound familiar, and if so, what do I do to kill the culprit? If not, what could be the likely problem?
Thanks

Any of the following sound familiar?

KEY TO COMMON AND IMPORTANT HOLLY PESTS

Japanese wax scale -White, waxy blobs up to 6 mm in diameter appear on limbs and twigs. They are often accompanied by sooty mold.

Native holly leafminer -Irregular, elongate, yellow or brown splotches on upper leaf surface (tunnels); small, chunky maggots in tunnel. (Adults rarely found.).

Southern red mite -Small chlorotic spots on leaf surface, heavily infested leaves becoming bronze in color; tiny, spiderlike animals (spider mites) on lower leaf surface usually in spring or fall.

Tea Scale- Cottony masses are evident on the lower leaf surface. Sooty mold may be present, and plant vigor may be impaired.

Kiasu