"It's from some futuristic planet or another." Like most things in Milliways. The names tend to blur together in Obadiah's head, especially the ones just barely pronounceable in human speech. "It's antiseptic with a mild anesthetic. It'll help keep the swelling down."

Which is almost a shame - he likes the way the developing ridges feel under his fingers - but won't hurt the visual aesthetics of the marks too much, at least.