Based on your description, it’s most likely a fascinating and somewhat mysterious fungus called Xylaria polymorpha. It’s also known as “dead man’s fingers” due to its distinctive appearance.

Here are some interesting facts about this fungus and what its presence in the garden means:

How to identify it:

Appearance: Grows in clusters (usually 3 to 6 “fingers”) directly on rotting wood, old tree stumps, or simply on woody mulch.

Color: Young specimens can be pale, grayish, bluish, or brownish (often with lighter, nail-like tips). As the mushroom ages, it eventually darkens, eventually turning black, and develops a wrinkled, charcoal-like texture.

“` Consistency: As you may have noticed, the fruit bodies are very hard, woody and contain a white, firm pulp.

Is it dangerous?

For humans and animals: The mushroom is inedible (it is extremely hard and woody), but it is not highly toxic on contact. If you have curious pets or children in your garden, it is best to collect the fruit bodies and throw them in the trash so that no one tries to taste them.

For your garden: The woodworm is a saprophyte – it feeds on the decomposition of dead organic matter. In bark mulch, it is a completely natural helper, contributing to the decomposition of wood and returning nutrients to the soil.

However, caution is advised in one case: If these fruit bodies do not grow from loose mulch, but directly on the base of the trunk or on the roots of a living tree or shrub, this could indicate that the tree is weakened or dying and that the fungus has colonized it damaged root system.

What to do?

If you don’t like the unsightly appearance, you can simply dig up the individual fruiting bodies, collect them with gloves and throw them in the household waste. However, complete removal is difficult because the mycelium is deeply rooted in the mulch or in the underlying, rotting wood debris. When the mulch dries out or decomposes naturally, the fungus disappears on its own.