id good or bad

I noticed these growing in my tank they have a hard shell and have some type of worm in them. They dont seem to bother anything but im concerned if there bad and could take over.

I like Vermitid Snails. I think they are strange but cool. They have never overpopulated for me perhaps because I tend to feed differently. Those pictured are the larger variety. The tiny ones build their calcium tubes about 1/4 - 1/2" high so they jab unsuspecting fingers when moving LR. These stationary snails send out a mucous net to capture food floating by, then pull in the net to eat the captured food and the net. I watch their fascinating behavior with a magnifying glass.