**Core Concept**
The development of the eye involves the formation of various structures from different layers of the embryo, including the neuroectoderm. The **neuroectoderm** gives rise to most of the ocular structures, but not all. Understanding the embryological origin of each structure is crucial for comprehending ocular anatomy and pathology.

**Why the Correct Answer is Right**
The correct answer is related to the structure that does not originate from the **neuroectoderm**. Most ocular structures, including the retina, iris, and optic nerve, are derived from the **neuroectoderm**. However, one specific structure is derived from a different embryological layer.

**Why Each Wrong Option is Incorrect**
**Option A:** This choice is incorrect because it is indeed derived from the **neuroectoderm**.
**Option B:** Similarly, this option is also incorrect as it originates from the **neuroectoderm**.
**Option C:** This choice is incorrect because it is derived from the **neuroectoderm** as well.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the lens of the eye is derived from the **surface ectoderm**, making it distinct from other ocular structures in terms of embryological origin. This distinction is crucial for understanding various ocular pathologies and developmental anomalies.

**Correct Answer:** D. Lens.