Gelatin

Gelatin is a substance created by thickening a liquid into a flexible semi-solid material.

Many types of gelatinous matter have their origin in biological lifeforms, but others have been created artificially for use as food, medicine or entertainment.

In 2266, Harcourt Fenton Mudd replaced his supply of Venus drug with edible gelatin capsules, causing a placebo effect in the women who ate them, proving that they did not need the drug. (TOS episode and novelization: "Mudd's Women")

While dining in the capital city of one of the nations of Beta Ophiuchi VI at some point in the 24th century, Ileen Maisel watched dancing gelatin. (TNG novel: Intellivore)

In 2369, while starbase Deep Space 9 was under siege by Meta, a rogue Changeling committing mass murders, Nog played a dirty prank, dumping gelatin through a conduit in order to panic security personnel and the space station population. His deception was quickly revealed by an angered Odo. (DS9 novel: "The Siege"