Social slime

the discovery is much more than a mere curiosity, because the colony consists of what are known as social amoebas. Only an apparent oxymoron, social amoebas are able to gather in organized groups and behave cooperatively, some even committing suicide to help fellow amoebas reproduce. The discovery of such a huge colony of genetically identical amoebas provides insight into how such cooperation and sociality might have evolved and may help to explain why microbes are being found to show social behaviors more often than was expected.

-- Oozing Through Texas Soil, a Team of Amoebas Billions Strong