The phrase "gelatinous material" refers to a substance that has a jelly-like texture or consistency. It is soft, smooth, and often wobbly, similar to gelatin dessert or jelly. Full definition
What's even more puzzling is that under their skin, the snailfish — which live in the world's deepest trenches — have either a layer or pouch of gelatinous material that pours out if the skin gets punctured. (sciencemag.org)
Successful traditional diets provided muscle meats together with organ meats and gelatinous materials such as bones, gristle and other connective tissue. (westonaprice.org)
Apple cider vinegar, and indeed all vinegar in its undiluted form, contains a slimy gelatinous material called the «mother». (supernaturalacnetreatment.com)