Caps are not flow-like animals, however, the flow rate significantly affects their growth patterns. The higher the flow rate the thicker and higher it grows - the lower the rate, the thinner and flatter it grows (this is from my experience, not scientific evidence)
Interesting. I've seen the same thing in my tank. I've got a cap in a high flow area and it's plated like crazy, whereas my cap in a lower flow area has grown in one large flat plate.