The stalks are still retractable even though they don't look like helix. 800x in brackish tide pool.
materials in an experiment: P1-P2 dyed individuals, P3 dead individual after adding acid
Seemed to have a stiff, clear stalk that did not contract.
Microorganism of focus is circled in red.
I found it while I was looking at a patch of algae(dark patches) under a microscope at 250x magnification.
Seek suggested that this microorganism is in the genus Frontonia.