Roosta is a hitchhiker and researcher for the Guide, whom Ford Prefect knows, at least in passing, and holds in some regard (Ford describes him as somebody who "really knows where his towel is"). He carries a special towel with nutrients infused into one corner, and barbecue sauce stains in an opposite corner, which can be obtained by sucking the towel (certain bits of the towel taste vile beyond all imagining, and for this reason, one part of the towel also contains anti-depressants to go along with the barbecue sauce, ostensibly for use when the vile nutrient-soaked end depresses him). He saves Zaphod Beeblebrox from a horrible death in the offices of the Hitchhiker's Guide (by taking him into the artificial universe in Zarniwoop's office), and is then kidnapped along with Zaphod and the left-hand tower of the Guide building by a squadron of Frogstar Fighters.