Hallucigenia is a 0.5–5.5 cm (³⁄₁₆–2 ³⁄₁₆ in) long tubular organism with seven or eight pairs of slender legs, each terminating with a pair of claws.
Above each leg is a rigid conical spine.
The 'head' and 'tail' end of the organism are difficult to identify; one end extends some distance beyond the legs and often droops down as if to reach the substrate.
Although some specimens display traces of a gut, the internal anatomy has not been formally described.

Recent research suggests that the extended element is an elongated head with two simple eyes, a mouth with radial teeth, and pharyngeal teeth within the front of the gut.

Hallucigenia's spines are made up of one to four nested elements.
The spine surface of Hallucigenia sparsa is covered in an ornament of minute triangular 'scales', while the spine surface of Hallucigenia hongmeia is a net-like texture of microscopic circular openings, which can be interpreted as the remains of Papillae.
 They may have also had hair-like setae lining their fine anterior appendages for use in filter feeding.
Hallucigenia is a 0.5–5.5 cm (³⁄₁₆–2 ³⁄₁₆ in) long tubular organism with seven or eight pairs of slender legs, each terminating with a pair of claws. Above each leg is a rigid conical spine. The 'head' and 'tail' end of the organism are difficult to identify; one end extends some distance beyond the legs and often droops down as if to reach the substrate. Although some specimens display traces of a gut, the internal anatomy has not been formally described.
Recent research suggests that the extended element is an elongated head with two simple eyes, a mouth with radial teeth, and pharyngeal teeth within the front of the gut.
Hallucigenia's spines are made up of one to four nested elements. The spine surface of Hallucigenia sparsa is covered in an ornament of minute triangular 'scales', while the spine surface of Hallucigenia hongmeia is a net-like texture of microscopic circular openings, which can be interpreted as the remains of Papillae.  They may have also had hair-like setae lining their fine anterior appendages for use in filter feeding.
Hallucigenia