As long as they aren't upsetting/harming the coral, ie it is balled up
ALL the time then the behavior is probably ok. Best to keep an eye on
them as some species of mushroom coral/anemones can east smaller fish:

http://www.wetwebmedia.com/corallim.htm

"robin.gordon1" wrote in message ...
my two juvenile clowns have suddenly taken a liking to my furry mushrooms,
as a proxy anemone. they roll on their sides among the furry(?) bits and
lay into the mushrooms at night. when feeding the mushrooms would
occasionally close up like an anemone. has this tricked them into thinking
that these are the real thing. both clowns are relatively young and only
about an inch long and as such I was advised that they would be difficult to
acclimatise to an anemone and so not to bother buying one.
is this behaviour ok to let continue or should I buy an anemone or maybe
move the mushrooms to another part of the tank.

Robin