spirallamella

Spirallamella is a descriptive term used to denote a structural motif in which lamellae—thin plates or layers—are arranged in a spiral around a central axis. The term does not imply a single universal form; rather, it covers various instances in which layered elements follow a helical path as they accumulate or grow.

Examples appear in biology, paleontology, and materials science. In some mollusk shells, lamellar programs responsible for nacreous or prismatic microstructures can exhibit spiral alignment along the shell’s growth trajectory, contributing to toughness and crack deflection. In certain microscopic fossils and microstructures, spiral lamellae appear as internal frameworks that reinforce the body plan. In engineered materials, spiral lamellae are studied as bioinspired motifs intended to combine lightness with strength; synthetic spirallamella‑like architectures have been produced with layering sequences around a core.

Formation of spirallamella structures typically involves sequential deposition of mineral or organic layers around a growth axis, with organic matrices and environmental controls guiding the geometry. The exact morphology depends on the organism or fabrication method and can vary from tight helices to loosely wound spirals.

Etymology: from Latin lamella (thin plate) and spiralis (spiral). See also lamella, nacre, spiral growth, biomineralization.