FIG. 1 is a perspective view of a new and ornamental design for a culture vessel block as viewed from above;
FIG. 2 is a perspective view thereof as viewed from below;
FIG. 3 is a right side elevation view thereof;
FIG. 4 is a left side elevation view thereof;
FIG. 5 is a front elevation view thereof;
FIG. 6 is a rear elevation view thereof;
FIG. 7 is a top plan view thereof; and,
FIG. 8 is a bottom plan view thereof.