You need to make a procedure that is applied to your block when its randomly updated (for example like the crops when they grow randomly) and then it when this procedure is triggered you look at different blocks around the one updated and if they match with blocks that could be replaced (if you want your block to expand only to stone for example) then you replace it with your block !
You need to make a procedure that is applied to your block when its randomly updated (for example like the crops when they grow randomly) and then it when this procedure is triggered you look at different blocks around the one updated and if they match with blocks that could be replaced (if you want your block to expand only to stone for example) then you replace it with your block !
Dont hesitate to ask for more !