Clathria lissoclada, the triangular blade sponge, is a species of demosponge from the southern hemisphere.
This stalked pink to orange sponge grows up to a length of and a width of . The somewhat flat branches arise from semi-triangular blades. The surface is smooth with many randomly distributed oscules. This sponge is semi-compressible and tough.
This species is found off the coast of South Africa and off the Falklands. It is found at depths of .
This species often has polyp-like invertebrates living on its surface.