is there some kind of wordplay at work with “placenta” and mount “Etna”, the volcano in Italy that was mythologically the forge of Hephaestus and the final resting place of Typheus? I couldn’t find anything convincing to explain the “place” part (which comes from Greek, “plax”, a flat plate), so probably not - but a fun fact I did learn from my trip to Wikipedia is that as Normans entered Sicily and spread the Arthurian romances through Europe, Etna became one of the locations of Arthur’s underworld kingdom, so there could be an established Excalibur connection, too