Which is this edible substance?

Chia seeds are the edible seeds of 'Salvia hispanica', a flowering plant in the mint family native to Central America, United States and Mexico.

Chia seeds are oval and gray with black and white spots, having a diameter around 1 millimetre (0.04 in). The seeds are hydrophilic, absorbing up to 12 times their weight in liquid when soaked and developing a mucilaginous coating that gives chia-based foods and beverages a distinctive gel texture.

There is evidence that the crop was widely cultivated by the Aztecs in pre-Columbian times and was a staple food for Mesoamerican cultures. Chia seeds are cultivated on a small scale in their ancestral homeland of central Mexico and Guatemala and commercially throughout Central and South America.

Typically, chia seeds are small flattened ovals measuring on average 2.1 mm × 1.3 mm × 0.8 mm, with an average weight of 1.3 mg per seed.

Chia seeds may be sprinkled or ground up on top of other foods. Chia seeds can also be mixed into smoothies, breakfast cereals, energy bars, granola bars, yogurt, tortillas, and bread. They can be soaked in water and consumed directly or mixed with any kind of juice to make chia fresca or with milk.

Chia seed pudding, similar to tapioca pudding, is made with a type of milk, sweetener, and whole chia seeds. Chia seeds may also be ground and made into a gelatin-like substance or eaten raw. The gel from ground seeds may be used to replace as much as 25% of the egg and oil content in cakes.