Organisms showing only asexual reproduction (e.g. bacteria, some protists, like the euglenoids and many amoebozoans) and unicellular organisms with sexual reproduction (colonial or not, like the volvocine algae "Pandorina" and "Chlamydomonas") are "immortal" at some extent, dying only due to external hazards, like being eaten or meeting with a fatal accident. In multicellular organisms (and also in multinucleate ciliates), with a Weismannist development, that is, with a division of labor between mortal somatic (body) cells and "immortal" germ (reproductive) cells, death becomes an essential part of life, at least for the somatic line.