**Core Concept**
Fissural cysts are a type of developmental anomaly that arises from the abnormal closure of embryonic fissures. These cysts are typically located in the midline of the body and can occur in various regions, including the skin, brain, and other organs.

**Why the Correct Answer is Right**
The correct answer will be one of the options that does not fit with the others in terms of its embryological origin. Fissural cysts are characterized by their formation from the abnormal closure of embryonic fissures. This is a key concept in understanding the development and pathogenesis of these cysts.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is actually a type of fissural cyst, such as a dermoid cyst, which forms from the abnormal closure of embryonic fissures in the skin.
**Option B:** This option is also a type of fissural cyst, such as a colonic diverticulum, which forms from the abnormal closure of embryonic fissures in the colon.
**Option C:** This option is not a type of fissural cyst, but rather a type of cyst that forms from the abnormal development of glandular tissue, such as a branchial cleft cyst.

**Clinical Pearl / High-Yield Fact**
Fissural cysts can occur in various regions of the body, including the skin, brain, and other organs. They are typically located in the midline of the body and can cause a range of symptoms depending on their location and size.

**Correct Answer: C. Branchial cleft cyst**