Just thought it might be a nerite baby cause I got some in my tank. You are right though cause I looked up the snail you named and that looks exactly like it.
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It is possible the death of a snail could cause cyano. It is caused by elevated nutrients.
If the tank was the size of a glass of water or the snail was as big as a fist. A snail isn't enough to cause a nutrient spike of any significance. Now if it was several snails or a fish, that would be another story.