Spontaneous expectoration as a means of obtaining sputum samples for cytological examination is a noninvasive technique that allows for the study of a variety of pathologies of the respiratory pathways (tumor, inflammatory, environmental, etc.). A further advantage of this technique is that it is easy to apply, the ‘‘pick and smear’’ method being the one used in the majority of cases to prepare cytological smears, stained, usually, employing the Papanicolaou technique. In the course of the microscopic examination of the cytological smears, various structures may be encountered that, at first sight, have nothing to do with the purpose of the examination. Here we describe the presence of a striking structure observed in a routine cytological preparation corresponding to a sputum smear stained employing the Papanicolaou technique. This structure (Fig. 1A) has a kind of basal ring or insertion zone, in the shape of a horseshoe, with a maximum diameter of 250 lm, from which protrude numerous long, narrow extensions in each of which two segments of different thickness can be appreciated, the larger directed towards the insertion zone (Fig. 1B). As the structure seems soft rather than rigid, and has a chitinous appearance, it was initially thought that it might correspond to a fragment of an arthropod, probably of aquatic origin in view of the length of the extensions.