Alternate "Hiding the Ring" strategies

[Raynor]

There's no evidence that ANY earthly force could destroy a Silmaril- except perhaps their maker, Fëanor.

However, in The flight of the noldor, Yavanna fears that Ungoliant might destroy the silmarils:

And thus the fear of Yavanna that the Silmarils would be swallowed up and fall into nothingness did not come to pass