Which was a very good episode, not pretty cerebral but extra in the vis­ce­ral horror sort that TOS and early TNG often managed to drag off effectively — it seems to get drawn in­spi­ra­tion from “Harmony of Terror” and “Wrath of Khan” with re­spec­tive to to sub­ma­ri­ne dog­combat design (also https://martinn109blx1.wikitidings.com/user