Garden Pests and Diseases: Please tell me what this is if you can!, 1 by mlm01

mlm01 wrote:
I had a nice Echinacea growing with a big bud about to open, now something has ripped the side of the stem. It looks like someone took a fingernain (or a tooth?) and raked the side of the stem and dug it out. This plant is about 2 feet tall.

I have seen a rabbit chewing on my lobelia and have since been having adventures in hardware cloth, with the scratches to prove it. Can a rabbit have done this?

I hope the picture is good enough.