Glowworms were tiny animals which glimmered in dark
environments.  Other versions of the legendarium In The Book of
Lost Tales, Beleg is said to have thought of glowworms when
seeing the bright light of Noldo crystal lanterns. Glowworms are
also said to have been creeping about the borders of the deep
pools of Murmuran.  See also - ↑ J.R.R. Tolkien, The Lord of the
Rings, The Two Towers, "The Stairs of Cirith Ungol" - ↑ J.R.R.
Tolkien, Christopher Tolkien (ed.), The Book of Lost Tales Part
Two, "Turambar and the Foalókë" , p. 78 - ↑ J.R.R. Tolkien,
Christopher Tolkien (ed.), The Book of Lost Tales Part One, "The
Coming of the Valar and the Building of Valinor", p. 74