A noun in The Etymologies of the 1930s glossed “seashell” derived from primitive ᴹ✶syalmā under the root ᴹ√SYAL (Ety/SYAL).
Noldorin
helf
noun. fur, fur, *hide
helf
noun. fur
half
noun. seashell
half
noun. seashell
heleth
noun. fur, fur-coat
A noun in The Etymologies of the 1930s glossed “fur” appearing beside N. heleth “fur, fur-coat”, both derived from the root ᴹ√SKEL (Ety/SKEL). Since N. helf seems to be the cognate of ᴹQ. helma “skin, fell”, I believe helf refers to both skin and fur together and hence = “✱hide”, whereas heleth refers to just the fur itself.
Conceptual Development: Various rejected forms appeared in The Etymologies, including halath “skin, fell” from an earlier version the root ᴹ√SKAL, revised to helath “skin, fell” before being deleted (EtyAC/SKEL). Possible precursors include ᴱN. gwadh “bark, skin, peel” vs. ᴱT. suada “hide” (PE13/146), and G. dafros “bark, skin, peel” (GL/29); see those entries for details.