Sun Lichen is a multiface growth block similar to Glow Lichen or Sculk Growth in Vanilla.

It has four variants: Cold Sun Lichen, Cool Sun Lichen, Warm Sun Lichen, and Hot Sun Lichen. Each variant provides increasing amounts of heat when stepped on by an entity.

Sun Lichen grows on cobblestone rocks in cold and snowy biomes. The biomes it generates in are specified by the biome tag frostiful:has_feature/sun_lichen_covered_rock.

Each Sun Lichen variant must be mined with shears in order to obtain it in item form.

Using bone meal on Sun Lichen will grow one block of the same variant, similar to Glow Lichen.

Sun lichen covered rock in a snowy tundra

Sun Lichen produces a light level of 0 / 2 / 4 / 6 depending on its level, from cold to hot.

Sun Lichen is a source of heat in the wild. It absorbs heat from the Sun during the day and will discharge it into any entity that touches it, damaging that entity a bit but also increasing its temperature, scaling with the Sun Lichen's level. If the entity has a temperature greater than 0, then it will set the entity on fire instead. All variants except Cold Sun Lichen can discharge heat Only entities that can burn will have heat discharged to them.

After discharging, each variant of Sun Lichen will transform into Cold Sun Lichen and will need to recharge. In order to recharge, it must be placed in sunlight (not block light). It will then absorb this heat at a rate proportional to the amount of sunlight present. If warm sun lichen is placed in an area with no sunlight (for example, a cave), it will instead slowly discharge its heat back into the environment, and become cold again.