Appears to be a ciliate protist called Vorticella.
Image source: Wikimedia (Author: Frank fox, 2010)
Vorticella always stood out to me because of their long, narrow stalk they use for anchoring with ciliate-lined bell-shaped oral end.
Image source: MicrobeWiki (originally from Haw River Program)
Fun fact from Wikipedia:
The stalk is made up of the ...