Pseudopodium:
A pseudopodium is a temporary protrusion of the cytoplasm of certain cells, especially amoeboid cells, used for movement and feeding. Pseudopodia extend from the cell surface and are used to capture food particles or to propel the cell. They are often described as "false feet" because they are not true appendages but rather temporary extensions of the cell membrane and cytoplasm.
Choanocytes:
Choanocytes, also known as collar cells, are specialized cells found in sponges. They have a distinctive structure, consisting of a flagellum surrounded by a collar of microvilli, which creates a current of water that allows sponges to filter food particles from the surrounding water. Choanocytes also play a role in gas exchange and waste removal in sponges. Additionally, they are involved in reproduction, as they produce sperm cells in some species of sponges.