That is mushroom spawn, it's basically an auger that has been sprinkled with spores then blended up and mixed with a substrate. Nutrient auger is a bit tough to keep clean of other fungi. You basically have to work in a really sterile environment to keep other fungi and bacteria out of your auger. Here's a long article roughly explaining how it's done https://sciencing.com/make-nutrient-agar-home-6317533.html
Oyster mushrooms are a pretty aggressive mushroom so you can probably get them to grow without auger.
You can also buy already infused auger and inject it into a substrate to try and get mushrooms to grow. https://www.amazon.com/Root-mushroom-Mushroom-Cultures-erinaceus/dp/B07J2X8SWK/ref=sr_1_6?keywords=mushroom+spawn&qid=1584364378&sr=8-6