spi·ril·lum 
(sp
ī-r
ĭl
əm)
n. pl. spi·ril·la (-r
ĭl
ə)
1. Any of several aerobic bacteria of the genus Spirillum, having an elongated spiral form and bearing tufts of flagellae.
2. Any of various other spiral-shaped bacteria, especially one formerly classified in this genus.
[New Latin Spīrillum, genus name, diminutive of Latin spīra, coil; see SPIRE2.]

spirillumSpirillum volutans