Early stage with two arms (post-oral).

Stage with four pairs of arms.

Stage with four pairs of arms.

Blastopore and ring of mesenchyme cells secreting the larval skeleton.

Intermediate stage between gastrulation and pluteus larva formation.

Skeleton formation of post-oral arms.

Embryos during early cellular divisions.

Lantern of Aristotle in the oral region.

Stage with three pairs of arms.

Larva with six arms.

Stage with three pairs of arms.

Oral region with the lantern of Aristotle in formation.

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.

Accelerated 25x.

Early eight-arm stage.

Larva with three pairs of arms.

Stage with four pairs of arms.