Q: Write an inquisitive question about a specific text span in a given sentence such that the answer is not in the text.
Sentence: The violet bottom - dwelling , prickle - backed spheres wriggling in the tank in Gretchen Hofmann ' s lab aren ' t really known for their speed .<sep>Span: Gretchen Hofmann ' s lab
A:
Who is this? Why do they have a lab?