Sometimes people call this "painting the tape" or "painting the ticker." It's a bot that is buying on a short-term automated schedule.
On one hand, the bot's operator might be legitimately averaging into a position. They are buying, but they don't necessarily want to use up all their powder at once, so to speak. On the other hand, the bot's operator might want to make the ticker appear "green" all day, which might psychologically affect traders. Traders who are on the fence or worried about being left behind on a move up might be persuaded into buying based on the bot action.
Personally, I just ignore these bots. But when the 0.000024 buy bots start getting replaced by the 1 BTC buy bots --- and this does happen sometimes --- that can actually start moving the market at these prices.