wormy thing

So I was doing a water change and saw a little worm on my nerite snail. I’m pretty sure it was a detritus worm, still a little unsure. I’m wondering if garlic or aquarium salt will kill them. I don’t have many options because I have scaleless fish, invertebrates

Ok so, I have this new nerite snail and it's been slow to move around but it is moving...but the thing I noticed today is that it's got this long tentril wiggling around it.  Is it a syphon or some other snail part? or like....a gross wormy thing?