Echigoshirayukidake (Japanese: 越後白雪茸), commonly called Basidiomycetes-X or BDM-X, is a sclerotium of Ceraceomyces tessulatus.

The mushroom, Basidiomycetes-X (BDM-X), echigoshirayukidake was identified as Ceraceomyces tessulatus, a member of the family Amylocorticiaceae based on the molecular analysis of ITS region and D1/D2 regions of rDNA.

Sequence similarity between the mushroom and Ceraceomyces tessulatus voucher KHL16429, Herb.

BDM-X forms hyphal masses in light pink colonies crowded with hyphae on the media.

As the shape of BDM-X depends on the environment in which it is cultured, the large hyphal masses of BDM-X for industry use can be formed, for example, on a sawdust medium (10 cm×10 cm×20 cm) after one year cultivation.