Also known as the lichen mimic mantid or Florida bark mantid, Gonatista grisea is very well camouflaged — I would never have noticed this 10mm baby if it had not moved! (When it’s grown, it will only be about 35-40mm long.) Their coloring resembles that of lichen, and they are practically invisible on tree bark.
Mantids in general are ambush predators, lying in wait for prey and grabbing it with their long, folding forelegs. The little spurs you can see on the forelegs help hold prey once it’s grabbed.
This may well be a Liturgusa maya, which looks similar but has longer antennae, but since those are much rarer, having only been recently introduced to Florida, and seem to have brighter patterns, I’m going with Gonatista grisea on this one. (It’s so hard to tell at 10mm!)