Pleased with his new "guard dog" Kain then turned to the last two rewards from the trial.
The first one was a small green bead the size of a marble that was his reward from the third trial. It seems to be a default trial reward for people that enter the relic, it's similar to a space ring but specifically able to allow spiritual plants entry while preserving their quality.
With the exception of seeds, since they are in a dormant state that doesn't require anything like oxygen to survive, most space rings can't contain other living things.
Therefore, preservation containers, which Kain typically uses to carry spiritual plants are relatively cumbersome to carry compared to space rings while not having particularly large spaces, this green marble was an extremely valuable reward for Kain.
