Mushrooms are more closely related to people than they are to any plant.
Also, "Malawimonads." That just looks fun. Also, "Protists of uncertain placement."
Another diversion: single celled organisms, how big can they get? A single slime mold is one cell and can cover a square foot.
Here's this candidate, members of the Xenophyophore, a . See http://www.newscientist.com/article/dn18468#.U73XFI1dVBI "Shunning the convention that single cells are microscopic, Syringammina is a brute, growing to a width of 10 centimetres – and sometimes even twice that." It's much larger than this ameoba that also creates a "test" or shell of sand: http://en.wikipedia.org/wiki/Gromia_sphaerica . An inch and half is still pretty large for what comes to my mind when one sees the word "amoeba."
Why one particular species of http://en.wikipedia.org/wiki/Caulerpa isn't the winner, i don't know: "A species in the Mediterranean can have a stolon more than 3 metres (9 ft) long, with up to 200 fronds." Then there's http://en.wikipedia.org/wiki/Acetabularia. This has only one nucleus, but grows to 10 cm high and has a defined structure (more like a mushroom).
So, you know, when you look at the wiki page for http://en.wikipedia.org/wiki/Valonia_ventricosa and see the claim that this 2 inch diameter bubble is "arguably the largest single-cell organism" i really have to go back to the algae Caulerpa.
Wait, no "In the genus Halimeda, whole seabed meadows may consist of an individual, single-celled organism connected by filamentous threads running through the substrate." http://en.wikipedia.org/wiki/Bryopsidales
I suppose i am not surprised that the single celled organisms get so large in the seas. They've had a very long time to evolve there.
This is also posted at http://elainegrey.dreamwidth.org/513113.html .