The Six Rings Algae, a creature that was coincidentally developed by Six Rings Celestial Sorcerer, was a creature created to destroy.
Its destruction could remove Celestial-craters and even dictate the remaining ancient rules in the craters. At the same time, it could not be eaten by other creatures, thus not able to form energy cycles.
The mere existence of this evil plant was an interruption to the balanced law of the Endless World. It would be removed or repelled by those laws. Therefore, other than nurturing and protecting them artificially in the Sorcerers World, it would be impossible for nature to provide a thriving environment for these kinds of creatures.
Facing such terrifying plants, Grimm and the lot naturally avoided them by going the other way around.