Lifespans are only an approximation. I have a zebra (nerite) snail that is almost 9 years old and they are meant to be 1-3 years. God knows how, she’s switched tanks about 4 times in that lifespan but she still going.
So far mine is 9 years old. Solo shrimp in a tank after he murdered the ghost shrimp in there with him.
Amanos are known to be weird methuselah shrimp, though I don’t know how one would survive in an emptied tank but frankly I wouldn’t put anything past them at this point, Murder Shrimp wasn’t supposed to be around this long in a tank that has never had a water change.
MafiaCub 
That sounds amazing, but I’ve never read anything like it.
My suspicion is that they are something else, other than Amano.
Some pictures would be really useful.
Google says 2-3 years like you said.
Were they in wet gravel for 2 weeks? Is that how they survived?
Pretty wild survival story, not sure about how they could survive 9 years.
Even 3 inches sounds long for them.
Lifespans are only an approximation. I have a zebra (nerite) snail that is almost 9 years old and they are meant to be 1-3 years. God knows how, she’s switched tanks about 4 times in that lifespan but she still going.
Even if they weren’t all female, breeding amanos is very labor intensive because the spawn require salinity.
So far mine is 9 years old. Solo shrimp in a tank after he murdered the ghost shrimp in there with him.
Amanos are known to be weird methuselah shrimp, though I don’t know how one would survive in an emptied tank but frankly I wouldn’t put anything past them at this point, Murder Shrimp wasn’t supposed to be around this long in a tank that has never had a water change.
I have a Amano, that I’ve had for at least 6 years, but since it’s most likely wild caught, it could be even older.