The Groske are a different race to the Graske, they are notably blue instead of pink in skin colour. Some Groske crash-landed and were found by U.N.I.T. in 2006. Since then they have earned their keep as workmen in U.N.I.T. bases. Groske can be mistaken for Graske if you have not met them before, as Clyde, Rani and Sarah-Jane find out in Death of the Doctor, but Groske seem to have a hatred for the Graske. This two-part episode is the first appearance of the Groske.