It's a good one

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Thanks, the rubber band made sense because i had it on hand and it's easy to adjust. You could do the same with a couple chopsticks and some tape too. Whatever you have will work.

I might not even fruit the pineapple if it roots. Might just keep it in the house as an air purifier/nice looking plant.
It's a nice looking rock, granite is a stable one too, so won't fuck up the ph of your water. You might find this interesting:
Suiseki is an art form like bonsai, but itās about finding rocks that look like landscapes/mountains and stuff instead of training trees.