When you touch the rain button, a grid showing the tile layout will appear over your island, reef, and polar region. Tap on a tile to see its statistics and to add rain or sunshine with the rain and sun buttons. Each tile has a landform type (use sun or rain to change it), an elevation (fixed), a food level, and a moisture level (sun/rain buttons).
The food level is influenced by the amount of moisture on the tile, but it will also rise or drop depending on the food levels of adjacent tiles. The food level of a tile needs only to satisfy the hungriest creature you find or place on it. Creatures’ food requirements do not add up!
The skull at the bottom is a pollution level indicator.
Adding sunshine or rain will change your terrain and cause the food level to change. On your islands and polar region, adding rain increases food. On the coral reefs it is the opposite. Careful not to spend energy by accident by touching the buttons when switching tiles. You can hide or show all of the animals on any tile by toggling the eye icon.
If you tap quickly back and forth between the rain and sun buttons several times in succession, you can make a rainbow. It only lasts a few seconds.