Hope it's ok to post on this 'old' thread but it's a similar issue. I'm trying to figure out if one of my two nerite snails is dead.
I heard a clink on Saturday evening at 10pm as a snail fell off the glass and likely hit a bit of decor. (I assumed it was the other of the nerite snails as he has deliberately been jumping off decor/glass for years in order to lie on his back which is clearly more comfortable for him, likely as they're prone to oedema as they age. Therefore, I didn't disturb the tank.)
When lights came on during Sunday afternoon at 3pm, I noticed the shell was up-ended on its side in a strange way - on the operculum which has been flattened where she has broken it squeezing through tight spaces over her life. I put her in the correct position, but she has never moved since.
I've checked on her welfare regularly but she's been retracted inside the shell ever since. She didn't react when my other nerite crawled over her repeatedly last night. I've done the "sniff test" but all is fine so far, and I certainly don't want to remove her until she's definitively dead, and earlier on this thread I read of snail(s) that resurrected after 5 days. This is most uncharacteristic of her. (My other nerite goes for prolonged spells where he doesn't move - but his muscle/innards are always protruding rather than ever retracted in his shell.)
I've only ever had the experience of one nerite that died - a baby that was attached to her back when I bought her, so I am not entirely sure what to look for. (The baby snail never smelt when it died but it did look similar with its muscle/innards retracted and the hardened bit underneath eventually 'collapsed' after a week of lifting her in and out of the tank daily to check.)
Any thoughts on this or looking at the attached photo of her re whether or not she is dead?
[Edited to add: additional photo taken of her removed from tank, at the angle I found her on Sunday - I wanted to check for myself whether she would have been able to pull herself right way up if she had landed at this angle, which I now think she would have; *if* she is dead, this makes me wonder if she fell off the glass because she died, rather than died because of the 17-hour delay potentially stuck in that position.]