Brown band on apple snail

[canthus13]

I have a medium-sized apple snail who recently went through a period of extreme heat due to the busy hands of an 8-year old. The tank temp went up to ~115 F, killing the betta tankmate. the apple snail, hornwort, dozen or so pond snails that hitch-hiked with the hornwort, and a tiny lone ramshorn survived the heat. The apple snail seems to be perfectly fine aside from becoming a daredevil that now likes to jump from the highest spots he can find, and a worrisome brown coloration to the new shell that started after the heat episode. He's grown a band of about half an inch since then that is brown and very slightly translucent. I attempted to get a pic, but he seems to have sensed this and hid behind the filter intake.

Would this band be indicative of the stress from the heat incident, or do you think it might be a calcium deficiency caused by the pond snails?


Tank stats:

5 gallon (Soon to be upgraded to a 40 gallon hex...)
~78F
params unknown at this point. (I'll be getting a testing kit soon)
1 Apple snail
a dozen or so tiny pond snails
1 tiny ramshorn
1 cherry shrimp
3 Cory cats
a ton of slowly disappearing algae

[canthus13]

Hah. caught him in the open. Here's some pics. They're pretty dim, but you can see the newer brown strip that has been steadily growing over the last couple of weeks.