Filamentous bacteriophage
Filamentous bacteriophages are a family of viruses (Inoviridae) that infect bacteria, or bacteriophages. They are named for their filamentous shape, a worm-like chain (long, thin, and flexible, reminiscent of a length of cooked spaghetti), about 6 nm in diameter and about 1000-2000 nm long.
Source: Wikipedia — Filamentous bacteriophage (CC BY-SA 4.0)