This is the Nipper from Super Mario Bros. 3, a little plant enemy that jumps up at the player.
Based on the extra byte (extension field in Lunar Magic), it can stay in place and jump when the player is above it, move around, or spit fireballs when the player is near. Check the ASM file for a list.
Even if I use valid extensions, this sprite crashes the game. I'm using either PIXI 1.1 or 1.2. I don't remember exactly which. I've had to switch PIXI versions a lot just to get everything working in my hack.
Is this sprite SA-1 comaptible, because the sprite doesn't show up in-game? And whenever I insert the sprite the extension values show up in LM, same thing happens with the fire snake but freezes the game.