The C-terminal domain of PDB:1hl8 is constructed of eight anti-parallel-strands packed into two-sheets of five and three strands, respectively, forming a two-layer-sandwich containing a Greek key motif [1].

1: Crystal structure of Thermotoga maritima alpha-L-fucosidase. Insights into the catalytic mechanism and the molecular basis for fucosidosis. Sulzenbacher G, Bignon C, Nishimura T, Tarling CA, Withers SG, Henrissat B, Bourne Y; J Biol Chem. 2004;279:13119-13128. PMID:14715651