Plasmids are found in both plant and animal cells, but they are more commonly found in bacteria.

Here's a breakdown:

* Bacteria: Plasmids are small, circular DNA molecules that exist independently of the bacterial chromosome. They are very common in bacteria and play a crucial role in horizontal gene transfer, allowing bacteria to share genetic information.

* Plants: Plasmids are less common in plants, and when present, they are typically smaller and less complex than bacterial plasmids. Some plants, like *Agrobacterium tumefaciens*, use plasmids to transfer genes to other plants.

* Animals: Plasmids are extremely rare in animals.

In summary: While plasmids are primarily associated with bacteria, they can also be found in some plant cells and are very rare in animals.