Help to solve this April fools joke!

The class (not sure the year group) was studying unicellular organisms and as it was 1 April (198x or 199x)… I had drawn a diagram on the board to show what a paramecium looks like (a cut down version of the images below) and it came to me to tell the class that “It was no coincidence that the paramecium had this particular shape” and with this a student said it looks like a foot. ‘Yes’ I said and this is because one common place where you can find a paramecium is in the inside of a shoe. With that I suggested that they remove a shoe and see if they could find the ‘beast lurking within’. After much tugging at laces and searching little was discovered, so I suggested that for some crazy reason the paramecium are found more often in a person’s left shoe rather than the right, probably as one sweats more from the left foot. This caused greater interest and more shoes were removed and sure enough a cry of joy emanated from  a student that they had indeed found one. Not to be outdone the reticent students who did not want to participate got right into the search and with this renewed effort more victorious screams were made. “Yes he’s right I see one!”. [Not sure how this was possible as any biologist would know these unicellular organisms  range in size from 50 to 330micrometers and can only be seen with a microscope]

I played along with this and enthusiastically went to check out their findings and obviously had to agree with them. “My you have!” I asked them to hold up the shoe that contained the paramecium (if you look the shoes triumphantly, all except for the one in pink, held aloft are indeed LEFT shoes and I quickly took the image (attached) then revealed the true nature of the story.

We all had a chuckle but there was more to come. The following day a wrapped shoebox appeared on my desk and upon opening it discovered hundreds and hundreds of cut out paper paramecium. (see attached image) It would have taken one person a considerable amount of time to do this and even if a number of students were involved in this devious ruse it would have taken a long time.

To this day I do not know who did this. I remember it fondly and have told the story to many people. I will always remember April Fool’s Day and would love to know the story from the student’s perspective.

NB – This took place BI (before the internet) and if one checks on https://en.wikipedia.org/wiki/Paramecium  you will find the following image and note the descriptive name.