Spirilla, a type of bacteria, are

Spirilla (singular, Spirillum) are a group of bacteria characterized by a corkscrew (spiral) appearance. They are Gram-negative bacteria and are characterized by motile structures known as flagella. ... For a long time, Spirilla bacteria were classified under the genus Spirillum.

Explanation:

answer the senate acts as the court in the case of impeachment,the senate holds the trial serving as the trial and acts as the trial jury;