Give it a snickers.
The Crystaline Entity isn't itself when it's hungry.
We still don't quite know what the culinary preferences of the CE are. After it ate the people of Omicron Ceti, it apparently wanted a salad, since the vegetation only died after the
Tripoli had done its brief and uninformative visit. But does it have salad often (and the biosphere then grows back, like after a forest fire, only without most animals but vegetation-only worlds are so common that nobody wonders)? Does it get its appetite sated with a mere shipful or settlementful of people (so it eating those does not result in such massive numbers of missing ships that anybody would notice) and the salad is collateral?
Keeping the beast well fed ought to be utterly trivial if all it wants is the biomass of a hundred or so people, every ten years or so. Or even if that's its daily intake. Keeping a quintillion beasts fed that way would be nontrivial - and would feeding platforms attract hordes of the beasts, and/or promote massive procreation?
And does it eat flesh? Or does it feast on minds, like such creatures typically do? Could its belly be kept safely full with replicated minds? Marr and Data seem to agree it "absorbs living matter", and the
Kallisko is sucked dry of anything organic. But Marr thinks the CE would also eat Data unless the android were in cahoots with the beast, so perhaps chewing up the matter is just a step in a process that aims at something else altogether, and a mind would seem to be the only thing Data has to offer.
Feeding of polar bears isn't a particularly popular means of protecting the endangered species
or of keeping it from raiding human habitats, but feeding is part of the trick where excess bears are sedated and whisked away to where they won't do harm. Starfleet could probably start relocating CEs by activating a blinking box that projects souls for them to eat, luring them into a trap of some sort, and flying them to a distance. Or then having the blinkie-box fly to a distance, with the CE following. But is there wilderness where Starfeet would let the creatures roam?
Ultimately, the CE is not a threat - compared to its apparent galactic record, pet guinea pigs kill more children. But if this is due to there only ever existing a single CE individual, the issue of choosing between the kids and the beast does arise. Yet how many sharks have you killed to protect your offspring?
Timo Saloniemi