Answer: ostiole

AnswerCrossword Clue
OSTIOLETiny sponge orifice.
OSTIOLESmall orifice in sponge.
OSTIOLESmall aperture.
OSTIOLEPore
OSTIOLESmall aperture
ostiolea small bodily aperture, orifice, or pore
ostiolesmall opening or pore, esp. in the fruiting body of a fungus
ostiolea small bodily opening