The 12th sphere
The 12th Sphere was a Delphic Expanse sphere encountered in 2153 by Enterprise NX-01.
This sphere was 6.3 light years from Triannon in the Delphic Expanse. D'Jamat's ship had been on a pilgrimage there for several months when discovered by Enterprise. As far as Enterprise could establish, it was completely identical even in the smallest details to Sphere 1 and Sphere 2. (ENT: "Chosen Realm")