| Substrate Origin | Biogenic Substrate |
| Substrate Class | Algal Substrate |
| Substrate Subclass | Rhodolith Substrate |
| Substrate Group | Rhodolith Rubble |
| Definition | Substrate that is dominated by living or non-living Rhodolith Rubble, with a median particle size of 64 millimeters to < 4,096 millimeters (Cobbles and Boulders). |