The Naturalist is a scholar who can be found in most libraries in Britannia. His field of expertise is insects, more specifically the Terathans. Lately he has found something new to study though, namely the Solen.
The Naturalist is very interested in the Egg Nests of the Solen Race, but because he is a scholar and not much of a fighter, he isn't able to go and study them himself. That's why he needs your help.
If you decide to help him, he will send you to study four Solen Egg Nests. To do that you must first locate an entrance to the Solen Hive, which can be a bit tricky because they move around sometimes.
Once you get inside the Hive, finding the nests shouldn't be too hard, they are large open areas filled with large Egg Sacs. Unless you are a friend of the Solen Matriarch, you will have to watch out for the Solen, who will probably not like intruders in their home.
When you have found a nest you will have to study it for a little while and note your findings, then you can move on to the next one and continue like that until you have studied all four of them.
With all four nests studied you can return to the Naturalist with your findings.
When you give the Naturalist your notes he will reward you with a rare colored seed that a Botanist friend of his has bred, it can be either Aqua, Magenta or Pink.
If you want to please the Naturalist a bit more and maybe get an extra special reward you can also choose to not return immediately after studying the four nests. Instead you can try to gain entry into the secret fifth nest, where the Solen keep their special eggs.
To get into the secret nest you will have to get hold of a Green Thorn, which is a resource from certain plants grown by gardeners. This Thorn will have to be planted in a sandy area, where it will somehow cause the sand to collapse and reveal a mysterious hole.
Jumping into the hole will get you into secret nest, where you will find the eggs you need to study. Once you are done you can return to the Naturalist.
The Naturalist will be very happy when you return to him and will reward you with a rare Fire Red Seed.