Randy - I've been hoping to answer your question about how anemones grow. I'm getting closer with the information in this book. One of my "aha" moments is that ALL anemones have bi-radial symmetry. Left and right sides are mirror images, as are top and bottom. The directive axis can be determined by lining up the siphonoglyphs at the edges of the mouth - they are at the top and bottom of the directive axis.
Because of this symmetry, all four quadrants of an anemone match (mirror image across the two axes), and growth must be balanced across all four quadrants. Tentacles occupy the space between internal mesenteries - therefore (and this is the question you asked earlier) it appears that an anemone grows tentacles radially in four rows at a time - one row in each quadrant. I can't say whether they show up first at the edge of the oral disk, the center, randomly, or all at once (and perhaps this timing differs based on species and environment). The important thing is that an entire row is one unit - tentacles don't just grow randomly.