A cave fisher produces its filament from glands in its body; when it reels in a victim, it generally eats the filament along with its meal. It's impossible to harvest new filaments from a dead cave fisher, but filaments harvested from living ones are incredibly light and strong, functioning as silk rope once the sticky adhesive on a length decomposes (which generally takes 3d6 minutes). A cave fisher's filament glands are useful in constructing sovereign glue and similar sticky magical items. A single cave fisher's glands count as 100 gp worth of raw materials, offsetting the total cost of the item's final creation.