I grew up calling these peat pellets.

Each Jiffy 7 seed starter is 1 1/2 inch diameter and 1/4 inch thick with a hollow spot to drop and retain the seed.

Moisten them and watch them expand 7 X their dry size.

They provide an ideal potting medium for delicate seeds.

See it here $119.95 (opens in new window)

The case has been kept clean and dry. It was opened for the photograph.