Acros will grow out like tree limbs and also at their base. I have some that eventually encrusted over the rock they were placed on. Given enough time and the right conditions, any coral will out and over. I had a snail drop into a millepora and over the span of a month, the mille encrusted over the shell.
*180 gal Display, 100 gal basement sump, 33 gal refugium, 3x250 MH, 2x160 VHO actinics, zoos, some softies, LPS & lots of acros and other SPS.
*100 gal prop tank plumbed into main system w/ 2x96 PC lights and 1x150 MH,