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The spectral features of HD 94509 are highly unusual, adding an extreme tothe zoo of Be and shell stars. The shell dominates the spectrum, showing linestypical for spectral types mid-A to early-F, while the presence of a late/midB-type central star is indicated by photospheric hydrogen line wings and heliumlines. Numerous metallic absorption lines have broad wings but taper to narrowcores. They cannot be fit by Voigt profiles.  We aim to describe and illustrate unusual spectral features of this star, andmake rough calculations to estimate physical conditions and abundances in theshell. Furthermore, the central star is characterized.  We assume mean conditions for the shell. An electron density estimate is madefrom the Inglis-Teller formula. Excitation temperatures and column densitiesfor Fe I and Fe II are derived from curves of growth. The neutral H columndensity is estimated from high Paschen members. The column densities arecompared with calculations made with the photoionization code Cloudy.Atmospheric parameters of the central star are constrained employing non-LTEspectrum synthesis.  Overall chemical abundances are close to solar. Column densities of thedominant ions of several elements, as well as excitation temperatures and themean electron density are well accounted for by a simple model. Severalfeatures, including the degree of ionization, are less well described.  HD 94509 is a Be star with a stable shell, close to the terminal-age mainsequence. The dynamical state of the shell and the unusually shaped, butsymmetric line profiles, require a separate study.

The Puzzling Spectrum of HD 94509