Stage with three pairs of arms.

Aboral surface (opposite to mouth).

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

Stage with three pairs of arms.

Archenteron invagination and ingression of secondary mesenchymal cells.

Ossicles of the lantern of Aristotle in formation at the oral region.

Stage with three pairs of arms.

Stage with four 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.

Oral region.

Aboral region (normal position).

Oral region with the lantern of Aristotle in formation.

Aboral region (normal position).

Early eight-arm stage.

Larva with three pairs of arms.

Oral region with the lantern of Aristotle in formation.

Early stage with two arms (post-oral).

Arm growing on an unusual site.

Aboral surface (opposite to mouth).

Oral region.