Here is a hunter that has never once given chase.
A heliozoan is a sphere with rays — dozens of them, dead straight, radiating out in every direction at once, each one stiffened from inside by a bundle of microtubules laid out in a pattern so regular it looks manufactured. The cell hangs still in the water and waits for the water to bring it something. When something touches a ray, the ray holds it. Then the ray shortens, drawing the catch inward, and the cell takes it in.
The word is sun animalcule, and whoever coined it was not being fanciful. But the more interesting resemblance is to a drawing. Ernst Haeckel built a career on plates of radiolarians and heliozoans arranged in perfect radial symmetry, and he was accused — correctly — of idealising them beyond what he had actually seen down the tube. Then you watch one of these, and the symmetry is simply there, in the water, unexaggerated.
One caution, which is also the reason this room’s label is vague where the others are specific. “Heliozoan” is not a family. It is a shape, and the shape has been invented more than once by organisms that are not closely related. Calling this one a heliozoan says almost nothing about what it is descended from — only about what it settled on.