Looking for algae food

[Jmason95]

I've seen pictures of an algae disc that sticks to the inside of your tank, which fish can pick at until it dissolves I assume. It appears to be about the size of a quarter. This looks like a good feeding alternative verses using a clip to hold sheets of algae/nori.

I've searched online vendors and can't find it.

Does anyone know the name of this product and where I can locate it?

Has anyone used it and like it?

TIA