Normal Thyroid : Colloid
Colloid is most commonly seen covering large areas of the slide as "watery" (translucent) and thin material. It can be seen as a translucent film with bubbles, folds, cracks and as circular "chicken wire" artifact (as shown here).
Colloid can also be seen as thick and opaque with sharp outlines (image 6). In some cases colloid can be extremely thick and sticky ("bubble gum" colloid). Smears that have a high ratio of colloid to follicular cells are generally benign thyroid nodules.
Image courtesy of: Ami Patel, MD.