New Tank 4 days snails already Good or Bad

Hi still new to this.
Tank running for 4 days and clearly have at least one snail possibly 3.
Can only assume came from live rock.
Too small to identify but completely white at moment. One is on glass, two possibles are on live rock.
All tank readings are good.
Can there be bad snails.
Is this a sign the tank is progressing well.

Any advice great fully received.