I suggest using super glue gel for the zoos. Take the zoos out, then apply a small blob to the bottom then carefully reach in the tank and press them to the rock of your choice. Wear glasses and or gloves if you have them, as zoos can be highly poisonous. For the mushroom, simply rubber band it to the rock. It will look funny for a few days, but it will attach itself to the rock at which point you can remove the rubber band. I'm not sure what the cute pink flowery thing is, but the super glue gel / rubber band will probably work for it too.
HTH