You're asking about organisms that lack a cell wall. Here's a breakdown:

* Cell Walls: These are rigid structures that provide support and protection for cells. They're found in plants, bacteria, fungi, and some protists.

* Organisms Lacking Cell Walls: The most notable examples are animals. Animal cells are surrounded by a cell membrane but don't have the additional structural support of a cell wall.

Here are some other things to consider:

* Protists: This group is diverse. Some protists have cell walls, while others do not.

* Bacteria: Most bacteria have cell walls made of peptidoglycan.

* Fungi: Fungi have cell walls, typically composed of chitin.

Let me know if you'd like more information about cell walls or the differences between different types of cells!