https://www.wired.com/story/biggest-threat-to-humanity-black-goo
It's a monster or a monstrous thing in several ways. It could be almost any shape or colour, but the black goo or black oil seems to be the most menacing. https://en.wikipedia.org/wiki/The_Blob#Plot , https://www.youtube.com/watch?v=QX4gSpmz3Q8
https://en.wikipedia.org/wiki/Star_jelly
Perhaps such things could be in all shapes and sizes.
Are The Star-Jellies Natural? (Star Trek Bestiary) https://www.youtube.com/watch?v=HdY1d0Nsyio
https://en.wikipedia.org/wiki/Creepshow_2#The_Raft , https://www.imdb.com/title/tt0092796/mediaviewer/rm777567233?ref_=ttmi_mi_all_pbl_82
https://en.wikipedia.org/wiki/The_Blob_(1988_film)#Plot , https://www.youtube.com/watch?v=T71KyOERMf4
The+X-Files: Threads of the Mythology – Black Oil https://www.youtube.com/watch?v=jOtEUKuGMNA
The Purity Virus (The X-Files Explored) https://www.youtube.com/watch?v=j3BNRC6PAiM
https://villains.fandom.com/wiki/Purity_(The_X-Files)
https://aliens.fandom.com/wiki/Black_Liquid
https://villains.fandom.com/wiki/Black_Goo
https://www.reddit.com/r/Whatisthis/comments/otepj9/some_sort_of_living_black_goo/
There was a case of dangerous slime on the loose in France a few years ago.
https://www.unexplained-mysteries.com/news/330309/killer-slime-has-closed-beaches-in-france
https://nypost.com/2019/09/08/killer-slime-that-can-kill-you-in-seconds-taking-over-frances-beaches
https://gamefaqs.gamespot.com/boards/191629-resident-evil-7-biohazard/74929335 , https://gamefaqs.gamespot.com/boards/191629-resident-evil-7-biohazard/74929335?page=2
https://desertshapes.blogspot.com/search?q=Sentient+Black+Goo
