What are gemmules?

Explanation

(i) It is a mode of asexual reproduction in sponges.
(ii) Internal buds caled gemmules are formed which is a hard hall, consisting of an internal mass of fooed laden archaeocytes.
(iii) Durin unfavourable conditions the spone disintegrates, but the gemmule withstands adverse conditions.
(iv) The gemmules hatch during favourbale conditions.