We've heard of clever little pebbles to keep your coffee warm, but now a concept designer featured over on Yanko Design has devised a set of gadgets to keep your bath warm too.

The Warm On pebbles have been dreamt up to stop your bath turning cold after you've been laying in it for a long time. They're designed to monitor and radiate heat to ensure the water constantly stays at the same temperature. Clever, huh?

The main aim would be to stop you wasting hot water by adding more, but we do wonder how much energy would be taken up by activating the pebbles?! Either way, they're a great concept and ideal for those that love long, relaxing bath times!

[Via Yanko Design]