The 0+ ground state of the 10He nucleus produced in the 3H(8He,p)10He reaction was found at about $2.1pm0.2$ MeV (Gamma ~ 2 MeV) above the three-body 8He+n+n breakup threshold. Angular correlations observed for 10He decay products show prominent interference patterns allowing to draw conclusions about the structure of low-energy excited states. We interpret the observed correlations as a coherent superposition of the broad 1- state having a maximum at energy 4-6 MeV and the 2+ state above 6 MeV, setting both on top of the 0+ state tail. This anomalous level ordering indicates that the breakdown of the N=8 shell known in 12Be thus extends also to the 10He system.
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