ascula

from The Century Dictionary.

• noun That stage of the young of sponges (as Olynthus, Sycon, Haliphysema) in which, after ceasing to be a free-swimming embryo, and before it has changed into adult form by the development of spiculæ in the ectoderm, or other modifications, it becomes attached to some support. Haeckel.
• noun The first period of attachment of certain sponges, namely, that in which the sponge has lost or is losing its collar, opening the primitive cloacal collar, and forming the first central cavity without lateral ampullæ. It corresponds to the protospongian stage of Haeckel.