The sea anemone Metapeachia tropica (Panikkar, 1938), which was described from Madras, India, and belongs in family Haloclavidae, has previously been recorded in the Republic of Singapore but without details of appearance and occurrence. We rediagnose Metapeachia and redescribe M. tropica to accommodate the specimens we studied from Singapore (35 individuals were collected and others were only observed in situ); we designate a neotype for the species. A specimen has a cream-colored column, a patterned oral disc, 16 tentacles, and a conchula. Specimens of another species of Haloclavidae occur rarely in some of the same places as M. tropica in Singapore; we describe it as Synpeachia temasek new genus, new species, based on 8 individuals we collected and others that were only observed in situ. An individual has a reddish-brown column, an oral disc that can be patterned like that of M. tropica, 20 tentacles, and a conchula. We infer S. temasek may range west at least as far as Pakistan. Specimens of both differ from the type specimens of the species described from Annam, Vietnam as Peachia mira Carlgren, 1943, which we have not found in Singapore. We provide a key to some members of the Haloclavidae that differentiates the new genus.