Siphonodentalium dalli is a species of deep-sea scaphopod mollusk in the family Dentaliidae. It is commonly found in soft sediment habitats of the deep ocean, where it burrows into the substrate. This species is adapted to extreme environments, thriving in cold, dark, and high-pressure conditions. Siphonodentalium dalli plays a role in the benthic ecosystem by contributing to nutrient cycling and supporting microbial communities in its habitat.