I just wish to thanks Mr. Keeline for the link to Jules Verne´s myths / Garmt´s Jules Verne page, and add something about the Coralie adventure, a topic which I believe Verne alluded to in Vingt mille lieues sous les mers, and I comment in my book Las claves de Julio Verne. La novela [de aventuras] de nueva forma (eLibros Editorial, digital edition, December 2020):
"Because of inconsistencies about the episode, Charles-Noel Martin, in his biography of Verne (1971), denies its veracity. However, Volker Dehs in 2005 cites a 1909 a source where Paul Eudel (1837-1911), an important citizen of Nantes, contemporary of Verne, says that the young man got on a small boat and tried to reach a ship named Octavie, heading to the Indies; which gives credibility to the occurrence of the episode of a frustrated journey, although its details are vague.
Jean Chesneaux attributes the episode to the overwhelming bourgeois atmosphere of lawyer Pierre Verne's family to claim a runaway, but asked about his youth and home by Robert Sherard in 1893 Verne replied "We were a very happy family". For others, it was the child's premature love for his cousin Carolina Tronçon that decided to embark to get her a coral necklace from the South Seas.
I prefer this romantic explanation because it fits well into the world of sailors, ships, and overseas products, which surrounded little Jules, and buzzed in his childish brain, "that soft wax in which every impression is recorded without the need to print very hard" (Le chemin de France, Part One, Chapter VI). These words of Natalis Delpierre, a Vernian character, whose name can be translated as "born of Pierre" like its creator, have in my opinion a biographical nature, like others of the same protagonist pointed out by Chesneaux.
The collar version is more plausible if it is taken into account what I believe a concealed allusion to the matter. As it is known, Caroline did not reciprocate her cousin's love and married in 1847; years later, the writer would make sailor Ned Land say: Well, I bought a pearl necklace for Katherine Tender, my fiancée, who later married someone else. Lucky that necklace only costs me a dollar and a half!" (Vingt mille lieues sous les mers, Part Two, Chapter II).
Verne used to cross and alter real names. Caroline Tronçon is Katherine Tender –note the coincidences of initials, some syllables and, partially, phonetics–, as the Dutch historian Arne Magnusson is the Arne Saknussemm of Voyage au centre de la Terre, or the aeronaut Nadar the Ardan of De la Terre à la Lune". (Translated from Las claves de Julio Verne…, Chapter I).
I do not know if my Coralie/Ned Land connexion is original. I have not found about it in works about Verne.
Guillermo Gómez Paz
P.S. Please, excuse my own translation from Spanish.
 Los mitos de un escritor extraordinario, Cristian Tello,https://jverne.net/los-mitos-de-un-escritor-extraordinario/, Febrero, 2016. The source cited by Dehs must be Figures Nantaises (See Illustrations below).
 Jean Chesneaux, Una lectura política de Julio Verne, Siglo XXI Editores S.A., México D. F. 1973, p. 19.
 Jules Verne re-visited, Interview published in T. P.´s Weekly, October 1903.
 For example, J. C. Acerete, Foreword to Veinte mil leguas de viaje submarino, Editorial Bruguera S.A., Barcelona 1969, p. 9. Also, S. Bordoy, Foreword to Julio Verne. Novelas escogidas, Aguilar S. A. de Ediciones, Madrid 1968, Vol. I, p. 11.