Coats of Arms are specific to an individual. Thus there is not truly such a thing as a
"family crest", although it is possible to find a coat of arms associated with
an individual of a particular surname.
Having said that, coats of arms sometimes employ themes similar to others
associated with the same family.
For example, the coat of arms shown here is one promoted as a "Johns coat of
arms". Often, when a coat of arms associated with the name Johns is found, it
carries the three birds shown on this one.
These are often described as "crows" or "ravens", but they are, in fact,
"choughs". Choughs are members of the crow family, and are found in Britain
around the steep cliffs of the west coast. They were found on the cliffs of
Cornwall, which does correctly associate the name Johns with the south-west
part of England. Choughs are distinguished by their red legs and red beak. A
picture of one is shown above.
The next coat of arms shown here is that of William Eborall, and was recorded
during the Heraldic Visitation of Warwickshire in 1682-1683.
Several coats of arms for different members of the Eborall family have been
found over the years, and all of them contain the three hedgehogs (sometimes
referred to as "urchins" or "porcupines"). This seems to be a common theme for
Eborall coats of arms.
Mr Duncan Currie of London was responsible for the research upon which I based
this Eborall information. I hope I've interpreted his information correctly -
any mistakes are doubtless mine.