The note of egg yolk, when masterfully rendered, presents a surprisingly rich, deeply creamy, and subtly custardy olfactory experience. It is dense and smooth, evoking a velvety texture rather than a liquid one, with an undercurrent of luscious warmth. There's an inherent richness, a golden, almost fatty opulence that can lean towards a delicate, slightly sweet savoryness, reminiscent of freshly whisked yolks destined for a crème brûlée. Its intensity is moderate but persistent, weaving into the composition with a soft, diffusive glow rather than a sharp projection. It typically behaves as a heart or even a foundational base note, imparting body, roundness, and a unique, comforting tenacity to other accords. It lacks the typical volatility of top notes, evolving slowly, settling into a skin-like, nourishing warmth, sometimes with a whisper of baked goods or a tender, milky warmth. The most artful renditions avoid any overt sulfurous or metallic nuances, focusing instead on its inherent richness and subtle umami-like depth.