I'm not saying that intelligence exists because there's some endgame that we partake in, but more that intelligence is a tool that we use to perpetuate and improve our existence, as far as I can tell. I'm wondering if there's anything a rock could use intelligence for.
I know you weren't, but sometimes people pick up on that sort of thing, so I got a bit pre-emptive.
We survive in the world (hopefully) through intelligence, as well as not being too inefficient in a physical sense and countless other ways, etc, for as long as 'luck' holds and our minds and bodies are up to the task.
Dumb rocks survive in the world if they're hardy enough to withstand the crashing of the waves/blasting of the desert sandstorm/etc.
(In reality, we slough off cells and create new ones, whereas rocks just lose surface particles (give or take some chemical reactions on various types), but from one POV a rock is a rock until it splits, even if it's become a pebble in the meantime. Maybe it can be considered to be "growing and developing", even if it's doing so by shrinking and settling into the scenery, carving its own hole in the bedrock substrate it lies upon... Etc.)
One difference is that we are progenitors of rough facsimiles ourselves (or at least our kind) if we're sufficiently succesfully/lucky in that endeavour. Rocks are essentially dormant until they are worn away and then may become 'seed' material for a sedimentary offspring. Or are heated and 'become' metamorphic. Or are taken deep, deep down below the mantle and melted to perhaps eventually become new igneous deposits. Plus loads of side-shoots of development that mean that after 'soilification' (whatever the word is) their silica is taken up into the leaves of certain plants and... well, it's stretching the analogy to call it a 'lifecycle'.
"Smart rocks" may be another thing altogether (or not). It's not the smartness, though, just that in order to have become smart, the rock might well have had to have developed as part of a pseudo-crystalline mechanism that propagates proper offspring rocks which would have had to compete with each other (rather than let themselves be ground up and mixed together as a sedimentary layer, with no real 'idea' behind it) and from which this smart rock may have arisen.
Although my idea of smartness of rocks would not mean a "rock monster" being, so much as a propagating 'meme' throughout a rocky interface or medium. That's because I rebel against a purely anthropocentric "Discworld Troll" idea, and so my imagination heads more for a banyan-vine idea. Perhaps mixed with the idea of the 'intelligent reefs' of Cohen/Stewart's SF book
Heaven.
Anyway, while the form of the rock (or the particular grouping and form of particles involved) of an intelligent rock might well change, a 'continuation of being' would be occur. Thus the survival of "The Rock". And as incomprehensible to ourselves, much as a bacterium (empowered with the basic understanding and ability to visualise) might have problems with the mass sloughing of our skin-cells
not being the death "self" for each and every one of those.
(Note that I'm not trying to compare ourselves with a single-cellular 'society', and thus extend the intelligent rock to something along the lines of a city or even a Gaia-like planetary entity, so don't take that away from this analogy. It really needs some thinking about to avoid that kind of connotation. OTOH, it's maybe something I can save up until
that argument needs to be made...
)