rotten rubber fernco what could cause this?

[titanif]

hello, i own a rental property and my tenant told me there was a leak under his tub. when i crawled in the crawl space a fernco fitting had completly disappeared. the two metal ring clamps on each side and the rubber beneath those clamps was all that was left. all the rubber that was supposed to connect the abs to the cast pipe was gone. ive never seen this and i am just wondering what could cause this? is it acid in the pipe? rodents? or is this something that can happen with time? any input would be appreciated.

thanks

 

[Breplum]

Not normal.
Rodents do LOVE rubber.

 

[Sponsor]

 

[Tuttles Revenge]

That sounds like a rubber coupling that doesn't meet code. The rubber could have rotted, but doesn't sound likely. I think its more likely what Breplum is thinking, food for rodents.