Where are cnidoblasts found?

The cells absent in the gastrodermis of $Hydra$ are

Which of the following symmetry is found in adult sea-anemone?

In animals belonging to the phylum $Coelenterata$ $(Cnidaria)$, cells performing similar functions aggregate to form which level of organization?

Match the following columns:

Column-$I$	Column-$II$
$P$. Brain coral	$I$. Adamsia
$Q$. Portuguese man-of-war	$II$. Meandrina
$R$. Sea anemone	$III$. Hydra
$S$. Hydra	$IV$. Gorgonia
$T$. Sea fan	$V$. Physalia
$U$. Sea pen	$VI$. Pennatula

In which animal is an undifferentiated layer called mesoglea present between the two germ layers?