The one that looks like it is blushing has a body that is a thin, crusty layer that grows on the surface of the bark or rock, forming a pale greyish-white to off-white patch. The crust is smooth and even, like a coat of pale paint. But if you look closely, you may see hints of red, a pinkish or reddish-orange tint that seems to glow from within. It is the lichen of the hidden colour, the one that looks like something is trying to show through, the one that makes you lean in closer. What makes it special is the hint of red. Haematomma lichen is one of the few lichens in New Zealand with a reddish tint. The colour comes from a pigment that is sometimes present in the fruiting bodies or in the crust itself. The red is not always visible. It appears only in certain light, at certain times of the year, on certain specimens. It is the lichen of the shy blush, the one that reveals its colour only when it is ready, the one that keeps you guessing. The haematomma lichen is a crustose lichen, meaning it grows flat on the bark or rock, like a crust of paint, rather than upright or leafy. Its body is a smooth, continuous crust, often forming circular patches or irregular stains. The fruiting bodies (apothecia) are pale pinkish to reddish-orange, often with a raised, paler rim. Under a hand lens, the apothecia are beautiful, tiny discs with a powdery surface. Biologically, the haematomma lichen is a partnership, a fungus and an alga living together. The fungus provides structure and protection. The alga provides food through photosynthesis. The apothecia are the spore-producing structures, releasing spores into the air. To find haematomma lichen is to find the pale patch with a hint of red. It is pale, crusty, and blushing, a living secret on the bark. You have to look closely. You have to catch it in the right light. You have to be patient. It is the lichen of the hidden colour, the one that looks like something is trying to show through, the one that proves that the most beautiful things are often the most subtle.