Answer: Not a parasite; Curschmann spirals
As nicely described by Anon, Curschmann spirals are spiral-shaped mucous plugs that are commonly seen in patients with asthma and other chronic obstructive lung diseases. They are formed when thick mucous accumulates in the patient's small airways and forms a plug or cast of the airways. These casts can then released into lower respiratory specimens such as sputum and bronchoalveolar lavage (BAL) fluid and be seen on cytology and microbiology specimens. Even though they can superficially resemble worms, they are easily differentiated by their lack of internal structures, long irregular shape, and variable diameter.