Connecticut is underlain by a wide age range of rocks, generally 60 million years old and older.https://mrdata.usgs.gov/geology/state/map-us.html#home
The interactive geology map will zoom in to show specific geologic formations.
In looking at the images you attached, it appears to be a glassy volcanic rock, probably a rhyolite with gas bubbles (the vesicles) caught in time as the rock chilled. Some of the holes have been lightly coated through secondary mineralization which is deposition of minerals from hydrothermal fluids moving through the rock mass. For a more specific identification, I suggest taking the rock to a nearby geologist. There are several good geology departments in the universities in the state. Geologists are also located with the Natural Resource Conservation Service and U.S. Forest Service. Your son has sharp eyes to see the "different" rock because a lot of the bedrock present in New England is granitic, forming the resistant "Monadnock" domes remaining after the continental glaciers retreated. Good find!