
Wow!
Not only a magnifcient image but a powerful exemple of a most important concept in evolutionary Biology:
Tunicates are classified toghether with vertebrates in the Chordata phyllum despite its highly different adult anatomy because the dorsal cord present in its embryos and larvae and lost in its adults (but present in us as vertebral column and spinal chord).
It's by far the best real image I ever seen showing it!.
I plan (with your permission

) to show it to my students.