testudinal
(tɛˈstjuːdɪnəl) or testudinary
adj (Zoology) of, relating to, or resembling a tortoise or turtle or the shell of either of these animals
[C19: from Latin testudo]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014