This type of snail are quite harmless, they don't damage plants.
(Although some other snails and caterpillars also hitchhike AND eat plants.)

But they are quite annoying because they multiply very fast.
You don't have too many, so you don't need to add their predators like loaches.
Just start by picking them up by hand whenever you find them going up the glass.
Don't crush them; some people got infected from doing that.
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