Cones are venomous, and dangerous to you. Nassarius snails have a soft proboscis not capable of stabbing anything.
Whelks, on the other hand, have a "spear". Some whelks can resemble Nassarius snails.
I've been keeping/selling Nassarius snails for over 10 years, with no issues. They are omnivores so they will eat meaty food (why they come out when you feed the tank). I suppose they'll consume a carcass that's left to rot, that's part of what they do, but they won't harm anything healthy and alive.
Jenn
Whelks, on the other hand, have a "spear". Some whelks can resemble Nassarius snails.
I've been keeping/selling Nassarius snails for over 10 years, with no issues. They are omnivores so they will eat meaty food (why they come out when you feed the tank). I suppose they'll consume a carcass that's left to rot, that's part of what they do, but they won't harm anything healthy and alive.
Jenn