If the moss isn't alive itself; Ten is wondering if maybe someone is controlling it with low level psychic. Still, who is bringing in the different moss species? Ten is out checking out the domes and trying to figure out why it's contained.

That's the only other pattern. It's inside. Not outside. He still comes - to inspect both the blood and moss. It's when The Doctor is licking the moss - he stops.

"Same as the others. Nothing significant"

Then to Bev warmly, "Hallo, I'm The Doctor. And you know what's usually good in these situations? Tea! Helps calm the nerves and good for the synapses."

Richard might be able to read between the lines that The Doctor found something and doesn't like what he found.