What is the origin of remora?

Remora comes directly from Latin remora “hindrance, delay,” composed of the prefix re– “back, backward, again” and the noun mora “delay, obstacle, pause.” Other English words ultimately derived from mora include moratorium and demur. Remora is first recorded in English in the early 16th century as a name for the suckerfish, which has sucking disks on its head by which it can attach to the likes of sharks, turtles, and ships. This name is found in Late Latin in the 4th century a.d., so called because the fish was believed to slow the progress of ships. In Book 32, Chapter 1 of his Natural History, Pliny the Elder (a.d. 23–79 ) gives mora as a classical Latin gloss of Greek echenēis, literally meaning “holding (back) a ship,” and marvels at the supposed power of these fish: “But alas for human vanity!—when their prows, beaked as they are with brass and with iron, and armed for the onset, can thus be arrested and rivetted to the spot by a little fish, no more than some half foot in length!” (translated by John Bostock and Henry T. Riley, 1855). Remora in the archaic sense “obstacle, hindrance, obstruction” entered English by the early 1600s.