Hydrated Halid Zoa Plants
The only way that you can restore your health is by standing next to hydrated Halid Zoa plants so if you are nearly dead you need to find one.
Playthrough Strategy Tips
Tip 1: If you're about to run out of seeds, plant your last one in fertile ground to make a new plant, and then harvest a fresh supply of seeds.
Tip 2: Each time you come across a new creature, look at the blank entries in your encyclopaedia to see what you should be trying to find out.
Tip 3: You can use the map to instantly travel between Martian caves if you've run out of a specific seed and need a quick resupply.
Tip 4: Standing next to hydrated Halid Zoa plants is the only way to restore your health, so find one if you're nearly dead.