What are those tiny snails at petsmart?

The last two times I went to petsmart to purchase new fish, a really tiny snail snuck into the bags with the fish. They're not mystery snails and I only notice them in the tropical tanks. One of them was so tiny that I didn't even realize it got into my tank until a month later. I decided to keep both... show more The last two times I went to petsmart to purchase new fish, a really tiny snail snuck into the bags with the fish. They're not mystery snails and I only notice them in the tropical tanks. One of them was so tiny that I didn't even realize it got into my tank until a month later. I decided to keep both snails because I couldn't bare just killing them. So my questions are:

1) What kind are they? They have blue bodies and yellowish-brown shells. They are smaller than a pea.

2) Will they end up taking over the tank if they breed? I heard some snails will only breed in saltwater, but my tank is freshwater.

3) If they do breed, do they lay eggs above water or underwater? I used to have mystery snails and getting rid of their eggs were easy because they were above water and quite noticeable.

4) Will they end up eating my live plants?

Thanks in advance!
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