The word ekka “hole” appeared in etymological notes from around 1964 (DD) as the basis for the second element of S. torech “secret hole, lair” (PE17/188). Helge Fauskanger suggested it might be Quenya (QQ/ecca), but I believe it is a primitive form, though its Quenya derivative would be ecca. Damien Bador suggested Q. ecca might also mean “den”.