Petal Power
The archaeal virus SIRV2 employs an unusual means of escaping from its host. A 7-faced pyramidal structure is formed on the host cell surface from virus-encoded 10kDa protein and opens like the petals on a flower (shown on the image) to release mature virus particles.
Image: Colored negative contrast electron micrograph of an isolated 7-faced pyramidal structure encoded by the virus SIRV2 in open conformation.