Haplota clavata is an erect bryozoan that initially develops as creeping chains of autozooids, with subsequent chains arising to form small branched tufts, up to a few millimetres high. Autozooids are elongate to oval and rounded at the tip. The autozooids either lack, or have a much reduced, slender proximal portion.
Haplota clavata is distributed around northern Britain. It has been recorded from the Firth of Clyde, Lamlash Bay, Arran and Shetland. Outside of the UK, it is known from Skagerrak and Iceland, and in North America between the Gulf of St Lawrence and Cape Cod. Its true geographic distribution is uncertain since H. clavata is an inconspicuous species that is easily overlooked.
The species is able to colonise algae, various hydroids, e.g. Sertularia, and other bryozoan species such as Crisidia cornuta. It ranges from the low water mark to 73 metres.