  Given an infinite set X and an ideal I of subsets of X, the set of all
finitary operations on X which map all (powers of) I-small sets to I-small sets
is a clone. In a 2001 article, G. Czedli and L. Heindorf asked whether or not
for two particular ideals I and J on a countably infinite set X, the
corresponding ideal clones were a covering in the lattice of clones. We give an
affirmative answer to this question.
