Who built the caves?

Yesterday, we found out that nine million years in the past, there were intelligent life-forms roaming about the surface of Deucado. From the outline of the fossil, it appeared that they were a more highly evolved version of the blankets. And they were really good cave carvers. I suspect it is because they wanted to get away from the more or less continuous rain of death from the sky. So that is how the Deucadons were able to make such a quick escape underground after the meteor fell that created Lake Eprehem:

     “I thought Bukky told me you built them,” Rome asked.
     “Naw, we fashioned them to our likin’ but they were already there.”
     “So what’s this got to do with anything?” Rei asked.
     Steben walked away. He opened a small chest and retrieved some objects. He returned with two metal rods in his hand. He held them out for Rei, Rome and Bonnie to see. They were chisels.
     “When our forefathers got down there, during the buildin’ phase, they found many of these. And the hammerheads, like there in the fossil,” Steben said, pointing up. “We have always held the belief that the caves were somehow built. The ceilings were always too smooth to be natural.”
     “Yes!” Rome exclaimed. “This is the very thing that I noticed in the Cathedral,” Rome said. “Do you remember me mentioning it to you?” she directed to Rei.
     “Yeah, I do,” Rei said. He looked at the chisels in Steben’s hands and back up to the fossil. “What does it all mean, Wally?” he asked.
     “I don’t know yet,” Wally said. “But it is an amazing coincidence, don’t you think?”
     Rei took a deep breath. He rubbed the back of his head where MINIMCOM had fused his skull not two weeks earlier. “This hurts my head,” he said. “It’s, it’s beyond sleek. It’s mind-blowing.”
     “We think so, too,” Wally said proudly. “We’re going to keep going but there is a lot more to this little planet than we thought.”
     Rei stood there, lost in thought. Bonnie nudged Rome who, in turn, nudged Rei.
     “Oh, yeah,” he said. “This is amazing stuff but it isn’t really why we came.”
     “Sure,” Wally said. He pointed and Steben left them to return the chisels to their packing case. “So why are you here?” Wally asked.
     “You know that somebody tried to kill me,” Rei offered.
     “Yeah, I heard,” Wally replied showing the proper amount of concern. “But you seem OK to me. Do you know who did it?”
     “Yes,” Rome interjected. “It was the two remaining members of the Darwin group named Dan Steele and David Troutman. Do you know them?”

Finally, we get to the questioning. Wally is a stand-up guy according to Rei so there really isn't any need for Rome to invoke her powers as a telepath. Let's see what Wally has to say.