with(plots):
with(plottools):
plots:-display(
   implicitplot3d(x^2 + y^2 + z^2 = 1, x = -1..0.85, y = -1..1, z = -1..1, style = surface, grid = [50,50,50]),
   translate(rotate(implicitplot3d(x^2 + y^2 + z^2 = 1, x = 0.85..1, y = -1..1, z = -1..1, style = surface, grid = [50,50,50]), 0, Pi, 0), 1.70, 0, 0),
axes = none, scaling = constrained, color = gray)