As a part of his routine aboard the Covenant
before the cataclysmic event that damages the ship
the android Walter checks the stored embryos. Nothing special has happened by that point, the colony ship and its crew and cargo (~40 crewmembers, 2000 colonists, a number of frozen human embryos) are still supposed to be safe (not just presumably so, but actually safe and unharmed - unless I missed something really important in the plot, that is).
However, Walter finds one of the embryonic capsules tainted black and disposes of it in a container labeled Biohazard.
Why? What has happened to that embryo?
Is it supposed to be a normal part of the ship's operation that a few of the embryos do not survive? If so, why is it disposed of as a biohazard?
Does this have any significance to the plot?