From Fallen London Wiki
yeah, i feel like you either go for this or the airags after claiming the 10 eyeless skulls and the rubbery skull. threnodies are a pain to get any other way (either spending urchin favors or 6-7 actions per threnody at polythreme/underclay), and this gives you a lot more. personally, i'm alternating between claiming threnodies and airags.