Apparently Seraphsidae is unnecessary spelling and should be
Seraphidae. Ca't remember the source of this info.

To my knowledge Fimbriidae includes two living genera:
F. fimbriata (Linné 1758) - IndoPacific
F. soverbii (Reeve 1841) - SW Pacific
The family goes back at least to the Jurassic eg Sphaeriola. They
inhabit sand in shallow water.

The genera of living Xenophoridae have been sorted out... there is
ONE, with two subgenera:
Xenophora
Onustus (sub)
Stellaria (sub)

Species with numerous attachments right to adulthood, with a blunt
periphery in which the shoulders  "rolls over" into the base are
Xenophora ss; peripheral projections are limited to the bulges
between attachments eg giganteum, conchyliophora, neozelanica, konoi.

Species in which the periphery is similar in rolling over, but is
much more narrowly carinate or flangelike and may bear long spines,
belong to subgenus Stellaria eg stellaris, digitata, calculifera
{=chinensis/sinensis}.

Species in which the peripheral flange is very thin and is glazed
basally be inductura are subgenus Onustus (=tugurium) eg indicum,
exutum, caribaeum.

Xenophoridae has a Cretaceous-Recent fossil history; Jurassic forms
do not belong here.

I am sure that many of the "species" are synonyms of others, and that
there are also probably new species hiding among them!