Red Cage Identification Guide

The Object in Front of You

Nothing else in a temperate wood or garden looks like this. Sitting on the ground, usually on mulch or leaf litter, is a hollow red ball made of struts - a closed lattice of fused arms enclosing an empty interior, with no stalk of any kind holding it up. Diameters of 5-15 cm are usual. The colour ranges from a strong coral or scarlet through orange-red to a duller pinkish red as it ages. Around its base sits the collapsed remnant of a white sac, and if you approach downwind you will already have met the smell: a heavy carrion odour, and probably a crowd of blowflies working the inner surfaces.

Because the structure is so unusual, identification here is less about running a key and more about reading construction details carefully, since the small family of lattice and star fungi differ from each other mainly in how their arms are joined.

Reading the Lattice

Start with the mesh. In this species the arms are fused into a genuine continuous network - a closed spherical to ovoid cage of polygonal windows, most of them four-, five- or six-sided. Crucially, there are no free arm tips anywhere: every strut runs into another strut at both ends. The meshes are irregular in size, generally largest around the equator of the ball and smaller near the top and bottom, and a typical specimen will show a dozen or more windows.

Now look at a single strut in cross-section, which you can do by snapping one. It is spongy and chambered, built from a foam of tiny cavities, and it is usually flattened or ridged rather than round, often with a shallow groove along the inner face. The tissue is brittle and wet and tears easily, which is why old specimens sag and lose their spherical shape, ending as a slumped red heap. Colour is strongest on the outer face of each strut; inner faces are frequently paler or partly masked by the spore slime.

The Gleba

The spore mass, or gleba, is the dark olive-brown to blackish-green slime smeared over the inner surfaces of the lattice, concentrated at the junctions where struts meet and often running in strings down the inside of the cage. Fresh material is glossy and sticky; after a warm day it thins out and the flies remove much of it, leaving the lattice comparatively clean and brighter red. That progression is worth knowing, because a freshly opened specimen looks nearly black inside while a day-old one looks unambiguously red.

The odour comes from the gleba, not from the arms. It is putrid and unmistakable at a couple of metres, and it is the dispersal mechanism: flies land, feed on the slime, and carry spores away on their feet and in their guts. Insect traffic on a lattice fungus is therefore an ecological confirmation rather than a coincidence.

The Base and the Egg

Always excavate the base gently with your fingers. The lattice erupts from an egg - a whitish to pale pinkish, roughly spherical to ovoid body 3-6 cm across, partly buried, with a tough outer skin and a thick gelatinous layer inside. Once the cage has expanded, that egg remains as a ragged, cup-like volva clasping the bottom of the lattice, sometimes half-buried and easy to miss. Running down from the volva into the substrate is one or more white cords of mycelium, thick and rooting, which trace back into the mulch or litter.

Finding the volva matters for two reasons. It confirms the fungus belongs to the stinkhorn lineage, and its size gives you a sense of how large a cage to expect: the entire lattice is compressed inside that egg before expansion, and the whole unfolding can happen in a few hours.

Sectioning an Egg

If there are unopened eggs alongside the mature specimen - and there usually are, because they fruit in flushes - cut one vertically. Inside you will see, from outside in: a thin white skin, a thick clear jelly, and then the folded lattice itself, already fully formed and already red or orange, packed in like a compressed spring with the dark gleba lying against it. Seeing that pre-formed red mesh inside the jelly is as good a confirmation as the open cage, and it also separates cage fungi from puffballs and earthballs, whose eggs are undifferentiated powder or firm dark tissue with no folded structure inside.

Spores and Why the Print Is Different

Do not expect a conventional spore print. There are no gills, pores or teeth, and the spores are not shot off into still air; they are embedded in slime for insect transport. To examine them, lift a smear of gleba on a knife tip, dilute it with a drop of water on a slide, and look under high power. The spores are very small, smooth, thin-walled and narrowly elliptic to cylindrical, roughly 4-6 by 1.5-2.5 micrometres, and pale individually even though the mass looks nearly black. Their minute size and cylindrical form are consistent across the stinkhorn group, so they confirm the family rather than the species.

Substrate, Season and Distribution

This is a saprotroph of rich, disturbed ground. Wood-chip mulch is the classic substrate, along with garden beds, compost-amended borders, leaf litter under hedges, park plantings and the edges of paths. It thrives where fresh organic matter has been spread and then wetted. Fruiting is triggered by warm, wet weather, so in Mediterranean and warm-temperate climates it runs from spring through autumn, while in cooler regions it appears mainly in late summer and autumn and is largely confined to mulched, heat-retaining urban ground. It is native to southern Europe and the Mediterranean basin and has been carried widely with landscaping material, so an isolated colony in a new region is usually traceable to imported mulch.

Separating the Look-alikes on Structure Alone

Octopus stinkhorn. Red and equally startling, but its arms are free: they rise from a common base and splay outward like tentacles, joined only at the bottom, and they taper to pointed tips. No closed windows, and the gleba is spread along the upper inner faces of the arms.

Column stinkhorns. Two to five thick vertical columns, joined only at the very top and quite separate along their length, giving an arched or wishbone outline rather than a mesh.

White lattice fungi. Genuinely netted like the Red Cage, and sometimes found in similar mulch, but they are white to pale cream throughout and their nets are often loose enough to detach from the volva and roll free.

Stalked lattice species. A short but definite stalk lifts a small red mesh clear of the volva. If there is any column of tissue between the volva and the base of the cage, it is not this species, whose lattice sits directly on the egg.

Starfish fungi. A short thick stalk topped by a flat disc from which slender arms radiate, often splitting into two, producing a star outline rather than a sphere.

Common stinkhorns. A single tall white stalk carrying a thimble-like head, no lattice at all, though the egg and volva are similar.

Field Checklist

Stalkless red ball of fused arms with closed polygonal windows; spongy chambered struts; dark slimy gleba on the inner faces; putrid odour and flies; white volva and rooting cord at the base; growing on mulch or enriched litter in warm damp weather.