A quick google shows it seems to be a well known classic hoax from the late 90s.
But there really are crabs and lobsters that live in trees and things, as do lots of type of mollusc (eg slugs and snails). So it isn’t completely silly.
So it’s not like a tree octopus is any more ridiculous than the coconut crab?
It seems there is no good way to know the truth anymore, as searching the internet might just find collaborating lies and conjecture…