One of my favourite chinese new year food items is 'black moss' (yes, in its dried form, it looks more like a piece of steel wool than a vegetable). It's better known by its auspicious chinese name, fat choy ('striking it rich').
Unfortunately, there are several reasons why I shouldn't be eating it, including the following:
1. it is a photosynthetic cyanobacteria (eew!);
2. overharvesting of the stuff in the Gobi desert is contributing to erosion and desertification;
3. it has no nutritional value; and
4. it contains a toxic amino acid linked to dementia.