Meristotheca papulosa (synonyms: M. japonica and Eucheuma papulosa) is a red alga, popular as a sea vegetable in Taiwan, where it is known as jiguancai (Chinese: 鸡冠菜; pinyin: jīguāncài, literally "cockscomb vegetable"), and in Japan, where it is known as tosaka-nori (Japanese: トサカノリ), which can be prefixed with aka (red) so as to distinguish it from the ao (green) and shiro (white) varieties.

The plant tissue varies in color from red to peach, the texture is fleshy and cartilaginous, and the shape is flat and leaf-like, with irregular deep forking divisions.

The surfaces of older individuals will grow warty or spiky protuberances.

It has isomorphic alternation of generations (the sporophyte and the gametophyte share a very similar appearance).

It grows on subtidal rocks 5–20 metres deep, and can be seen at all times of the year.