In biology a spore is a unit of sexual (in fungi) or asexual reproduction that may be adapted for dispersal and for survival often for extended periods of time in unfavourable conditions. Spores form part of the life cycles of many plants algae fungi and protozoa. Bacterial spores are not part of a sexual cycle but are resistant structures used for survival under unfavourable conditions. Myxozoan spores release amoeboid infectious germs ("amoebulae") into their hosts for parasitic infection but also reproduce within the hosts through the pairing of two nuclei within the plasmodium which develops from the amoebula.