This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
'Inveed fir tree' appearance is characteristic of? 
Select and explain. 
A. Bacillus anthracis, B. Haemophilus influenza, C. Yersinia pestis, D. Brucella
A: Bacillus anthracis
Answer: A: Bacillus anthracis 
Explanation: B anthracis has a tendency to form very long chains of rods and in culture it is nonmotile and nonhemolytic. Colonies are characterized by a rough, uneven surface with multiple curled extensions at the edge resembling a "Medusa head." B anthracis has a D-glutamic acid polypeptide capsule of a single antigenic type that has antiphagocytic propeies. B anthracis endospores are extremely hardy and have been shown to survive in the environment for decades. On gelatin stab culture a characteristic inveed fir tree appearance is seen, with slow liquefaction commencing from top. Ref: Ray C.G., Ryan K.J. (2010). Chapter 26. Corynebacterium, Listeria, andBacillus. In C.G. Ray, K.J. Ryan (Eds), Sherris Medical Microbiology, 5e.