The ship's captain, Saybrook, analyzed the planet's abundant plant and animal life and discovered that it is all part of a single organism with a unified consciousness.
Unknown to the research ship's crew, they carry a stowaway — a part of the planet's fauna that crawled aboard when they temporarily dropped their force fields.
The planetary organism has never before experienced selfishness and violence and is desperate to "help" the "life fragments" (Earthlings) to become "complete", by joining consciousness with it in blissful unity.
If the stowaway manages to reach Earth, it will eventually convert all life there into a single organism with a unified consciousness — and green patches of fur instead of eyes.
The creature is greatly saddened by being disconnected from the planetary consciousness, but takes solace in the fact that it will soon perform its mission and join with all life on Earth.