thecae

Webster's Dictionary (GCIDE)

Theca \The"ca\, n.; pl. Thecae. [L., fr. Gr. ? a case to put anything in. See Tick a cover.]

1.A sheath; a case; as, the theca, or cell, of an anther; the theca, or spore case, of a fungus; the theca of the spinal cord. [1913 Webster]

2.(Zool.) (a) The chitinous cup which protects the hydranths of certain hydroids. (b) The more or less cuplike calicle of a coral. (c) The wall forming a calicle of a coral. [1913 Webster]