There are still some cool edge-cases. Is a sperm cell alive? An X-chromosome sperm (do X-chromosome sperm have a (probabilistic N)-stage lifecycle?) Are red blood cells alive? Is every molecule of an organism that's alive also considered alive, or just the ensemble? If only the ensemble, are mitochondria alive?
Also, why we consider a single human as living organism, but not a society? Single human without society is a pitiful and helpless chunk of meat, who unable to replicate btw.
Sperm cells can be seen as a haploid phase of many organisms' lifecycle, so are alive by pretty much any definition.
In humans, the haploid phase of the lifecycle is single-celled, while the diploid phase is multicellular. In contrast, in mosses and fungi the haploid phase is multicellular while the diploid phase (sporophytes/zygote) is single-celled.
The unfertilized eggs of bees become drones, so they must be alive. As a side effect, this indirectly make bee-like insects evolve a lifestyle with a big colony with a queen.
In fungus, most of the life is as haploid (i.e. a single copy of the chromosomes, like sperm and eggs) instead of diploids (i.e. two copies of each chromosomes, like most of our cells.)
In some ¿unicellular organism? [I can't find a good link now] the haploid and diploid versions are almost equal.
[And plants are also weird, some have 4 or 6 copies of the chromosomes instead of 2.]
