My son got 2 mystery snails about 2 1/2 years ago. He named the gold one "Day" and the black one "Night". We finally decided this morning that night had passed away. His door has remained open for several days and he has been floating. Today he failed the smell test and he was oozing slime. He was in our senior citizen planted tank. Everything living in there is old. We will miss him and I think the other "seniors" will miss him too.