A kettle fining derived from seaweed. Add 1 teaspoon per 5 gallons to the last 15 minues of the boil to enhance cold break (protein coagulation).
I have used Irish Moss in the last 7 or 8 batches of beer I've brewed. It seems to help with clarity and is inexpensive. I would recommend it to other home-brewers.
I was expecting it come in a jar (like the picture shows). Mine came in a small bag.
Does what it is supposed to do I think
Always adds an interesting note to your batch.