I wouldn’t be surprised if the initial purveyor of poo was a researcher, because they are always hauling weird shit around. I was once asked why I was carrying around 40 toothbrushes and when I responded with “for fish stuff”, the looks only turned more confused. I can only imagine being a well-traveled researcher trying to return through customs with my latest batch of study materials.
Some fish have little “hairs” on their body that are very similar to the “hairs” humans have in their ears to detect sound. As part of a trial to regrow damaged “hairs” in people with noise-induced hearing loss (soldiers, factory workers, etc), we had to uh, induce some damage so there was a test subject for the drugs. Turns out, tooth brush heads work really well for transmitting high-frequency waves through small volumes of water. Also turns out that I was not cut out for trials requiring living things. It was rough on the psyche.