Aboral surface (opposite to mouth).

Accelerated 6x.

Oral region with the lantern of Aristotle in formation.

Polarized light highlights the calcareous skeleton showing the structure of spines, podia, and remnants of the larval skeleton.

Stage with three pairs of arms.

Oral region with the lantern of Aristotle in formation.

Polarized light highlights the calcareous skeleton showing the structure of spines, podia, and remnants of the larval skeleton.

Oral region.

Lateral view. Detail of the lantern of Aristotle under the peristomial membrane (where mouth will open).

Larval pre-oral arms on a eight-arm pluteus.

Lantern of Aristotle in the oral region.

Esophagus.

Larva with four pairs of arms.

Tip of antero-lateral arms.

Growth of antero-lateral pair of arms (2nd pair).

Anus and anal plate.

Stage with three pairs of arms.

Found during an artificial fertilization experiment. We do not know if it is the result of abnormal development or if the larva was reproducing asexually.

Early eight-arm stage, lateral view.

Stage with four pairs of arms.