‘Possibility is not reality; but it is in itself a reality.’
‘The fact that the shell is carried for future use…’¹
No.
‘The only benefit is the potential future deployment of the shell(s)…’²
Yes.
Possibility is in itself a reality. Octopuses - alone among non-human animals? - clearly read Gramsci. Potentiality is a, not the, future, and whoever prepares for it also prepares for not-it, its non-occurrence, steps thereby outside teleology and inhabits more than one world. Hope won’t do: it takes anxiety. Dangling an ant-fishing twig in one’s great-ape hands is merely to aspire, to audition for the (only) future: if it remains unused one is nothing but a failed telonaut.

To straddle alternates a dreaded outcome is necessary. (So is OCD a surplus, an accursed share of humanity, sentience-plus?) The octopus like us negotiates a landscape of utinams and what-ifs.
‘Whilst being carried, the shells offer no protection and place a requirement on the carrier to use a novel and cumbersome form of locomotion - “stilt-walking”.’³

By what other name could we stilt-walkers know that motion out of the temporal monoline of instinct to this uncertaintyscape?
………………
¹ Finn, Norman, Tregenza, 2009, ‘Defensive tool use in a coconut-carrying octopus’, Current Biology, Vol.19 No.23, R1069-70, at 1070.
² Ibid. Emphasis added.
³ Op.cit., at 1069.