The Amoeba is a Prime Roots Flora. Though technically it's not a plant but a plazmoid.
It's scientific name is Dziku. It appears in 3 variants, seen on the right.
In most of the Prime Roots, the Dziku you'll encounter will be nothing but scenery. But in the Kitins' Lair some of them can be targeted and killed. Killing these is part of the Medic and Scrollmaker occupations.
The 3 variants can be seen from left to right in the image on the right.