It also had fewer spines than many of its relatives. Each of the paired pectoral and pelvic fins had a spine, as did the single anal and dorsal fins, giving it a total of just six, less than half that of many other species. +
A fossil discovered near Hamilton, Kansas in the Upper Carboniferous Hamilton Formation, and published in 2014 as Acanthodes bridgei was so well-preserved that traces of its eye tissue were sufficient to establish that Acanthodes had both rod and cone photoreceptor cells, and thus profited from color vision.
This site contains all information about Acanthodes.