Wow! A parent on the sight Nice to meet you! I am currently on my 1st generation and maybe the mysterious reason is because she didn't look at it for a few hours and might have been sick? Hope I helped
I am going to guess that they can live . . . forever. Probably up to its 99th generation. Anyway, somebody who I know's tamagotchi always dies for know reason what so ever. I am starting to think that is because it was neglected so much (and trust me . . . it was!) that it just died. Maybe . . . if I'm correct with the whole "neglected" theory . . . that's what happened to your daughters tamagotchi. I hope I helped you out a little. Good Luck with your next tamagotchi . . . I hope that doesn't happen again.
The Tama that mysteriously died was only 3 years old. (Very bizarre!) Each previous generation (6 of them) evolved perfectly. They each found love via the matchmaker, were married, had babies, and the cycle continued.... (My daughter's really great with tending to the Tamas.) She never neglects them - and I even "babysit" sometinmes. LOL!
As you can imagine, we're really stumped as to why this one died.
If anyone has any ideas, we'd appreciate hearing them.