many biologists are now of the opinion that Boojums, snarks and jabberwocks are different life stages of the same organism. They haven't quite agreed whether there is an alternation of generation thing going on or if possibly a metamorphosis but most do agree that boojums occur in both an aquatic form that is typically mobile - and a non-aquatic form which may or may not be sessile. Posible the sessile land form is a boojum entering into pupation.