Arcella Discoides

Arcella discoides is an amoeba in a sombrero. In young specimens, the wide-brimmed shell is transparent, and the little animal inside can be seen clinging to his hat with extended pseudopodia. As they age, the iron-rich shells get rusty, turning the sombrero reddish and opaque. Through the opening at the bottom, the amoeba can move around and grab a meal.