In this visual depiction of Fort Jefferson's walls, a cross-section reveals the contrast between the still-standing brick wall and the crumbled remnants beneath the water's surface:

**Above the Water: Still-Standing Brick Wall:**
- **Weathered Bricks:** The cross-section exposes a still-standing brick wall rising above the waterline. The bricks, weathered by time and exposure to the elements, carry the marks of history.

- **Historical Resilience:** The sturdy structure of the still-standing wall reflects the historical resilience of Fort Jefferson. The bricks, though worn, stand as a testament to the endurance of this 19th-century fortress.

**Below the Water: Crumbled Walls:**
- **Submerged Remnants:** Beneath the water's surface, the cross-section reveals the remnants of crumbled walls. Disintegrated bricks, softened by the constant embrace of the sea, form a submerged layer, mirroring the passage of time.

- **Integration with Coral:** The crumbled bricks have become a substrate for coral growth. Coral formations, in vibrant hues, cling to the disintegrated bricks, creating an underwater tableau that blurs the lines between the man-made and the natural.

**Marine Life and Coral Integration:**
- **Schools of Fish:** Schools of fish swim around the underwater ruins, adding movement and life to the scene. The crumbled walls serve as a habitat for marine life, fostering an ecosystem that has embraced the historical remnants.

- **Coral Integration:** Coral formations have intricately woven into the crumbled bricks, forming a harmonious integration of nature and decay. The coral's vibrant colors contrast with the subdued tones of the weathered bricks.

**Sunlight Filtering Through Water:**
- **Dappled Sunlight:** Sunlight filters through the water, creating dappled patterns on the submerged ruins. The interplay of light and shadow adds an ethereal quality to the underwater scene, accentuating both the architectural remnants and the marine life.

**Historical Echoes and Natural Transformation:**
- **Echoes of History:** The cross-section embodies echoes of history as the still-standing wall stands alongside the crumbled remnants. It speaks to the fort's enduring presence and the transformative effects of time and nature.

- **Nature's Reclamation:** The scene captures nature's ongoing process of reclaiming and transforming human-made structures. The integration of coral and marine life with the crumbled walls signifies the cyclical nature of decay and rebirth.

**Emotional Essence:**
- **Poignant Harmony:** The cross-section of still-standing and crumbled walls at Fort Jefferson creates a poignant harmony of past and present, history and nature. It invites reflection on the dual forces of resilience and transformation that shape this unique underwater environment, offering a glimpse into the coexistence of human history and the regenerative power of the natural world.