Lycoplanine A (1), a Lycopodium alkaloid with a 6/9/5 tricyclic ring skeleton fused with the γ-lactone ring and featuring an unusual 1-oxa-6-azaspiro[4.4]nonane moiety and an unprecedented 3-azabicyclo[6.3.1]dodecane unit, was isolated from the club moss Lycopodium complanatum. The structure and absolute configuration of 1 were identified by a combination of NMR spectroscopic analysis and single-crystal X-ray diffraction. Biological studies showed that 1 is a potent Cav3.1 T-type calcium channel (TTCC) inhibitor with an IC50 value of 6.06 μM.