Sea urchins are virtuosi of biomineralization, the process by which organisms build mineralized tissues. The embryonic animal exemplifies this with the formation of its endoskeletal spicule. The primary mesenchyme cells (PMCs) undertake spicule synthesis, which involves deposition of the initial granule, elongation of the spicule, and several choreographed changes...
The mechanisms governing selective CaCO3 crystal nucleation in living organisms remain unclear. For example, nacreous layers from the inner surfaces of shells are built as brick-and-mortar complexes of plate-like aragonite single crystals and organic layers. Unstable [001] surfaces of calcite columns in prismatic layers are also stabilized by organic molecules....