#nodules

• Amygdaliform — Having the shape of an almond; ovoid, elongated, and slightly flattened at the ends, presenting a specific biconvex geometry. This structural descriptor is widely used in anatomy to define nuclei or organs, in mineralogy for rock aggregates, and in archaeology to classify chipped stone axes from the Paleolithic era.
• Bacteroid — A modified, enlarged, and often branched form adopted by nitrogen-fixing bacterial cells (such as Rhizobium) after entering the host cells within the nodules of legume plants. Physiologically, the bacteroid stage represents the active metabolic phase where the microorganism loses its rigid cell wall and begins synthesizing the nitrogenase enzyme complex responsible for nitrogen fixation.