'Artex' is a common name for proprietary ceiling covering found on ceilings.  Typically it is applied in a pattern of' swirls' that tends to fad in and out of fashion.  It can be difficult and expensive t remove.

More concerning, Artex applied to the ceilings of older properties (pre 1980's) can have some asbestos content and should be treated with suspicion.  The asbestos was used to strengthen the artex however it will degrade over time.  If there is any doubt (especially if it has started to powder) you should seek the advice of an asbestos surveyor as soon as possible